Replace proprietary headers with Apache 2.0 copyright headers in PrivacyGuard shadow_model_training (#98)

Summary:
Pull Request resolved: #98

Adds Apache License 2.0 copyright headers to seven source and test files under privacy_guard/shadow_model_training, replacing the internal confidential header. This aligns the repo with OSS compliance and satisfies the COPYRIGHT_HEADERS_EXIST check from the Open Source Automated Checkup.

These files were recently added w/ the shadow model training module.

```

COPYRIGHT_HEADERS_EXIST: Copyright Headers
****************************************
FIX IT! https://our.intern.facebook.com/intern/opensource/github/repo/2059348974551169/repo_settings/header_exemptions/
Every project specific source file must contain a doc block with an appropriate copyright header. Unrelated files must be listed as exceptions in the Copyright Headers Exceptions page in the repo dashboard.
A copyright header clearly indicates that the code is owned by Meta. Every open source file must start with a comment containing "Meta Platforms, Inc. and affiliates"
https://github.com/facebookresearch/PrivacyGuard/blob/main/privacy_guard/shadow_model_training/dataset.py:
The first 16 lines of 'privacy_guard/shadow_model_training/dataset.py' do not contain the patterns:
	Copyright
https://github.com/facebookresearch/PrivacyGuard/blob/main/privacy_guard/shadow_model_training/model.py:
The first 16 lines of 'privacy_guard/shadow_model_training/model.py' do not contain the patterns:
	Copyright
https://github.com/facebookresearch/PrivacyGuard/blob/main/privacy_guard/shadow_model_training/training.py:
The first 16 lines of 'privacy_guard/shadow_model_training/training.py' do not contain the patterns:
	Copyright
https://github.com/facebookresearch/PrivacyGuard/blob/main/privacy_guard/shadow_model_training/visualization.py:
The first 16 lines of 'privacy_guard/shadow_model_training/visualization.py' do not contain the patterns:
	Copyright
https://github.com/facebookresearch/PrivacyGuard/blob/main/privacy_guard/shadow_model_training/tests/test_dataset.py:
The first 16 lines of 'privacy_guard/shadow_model_training/tests/test_dataset.py' do not contain the patterns:
	Copyright
https://github.com/facebookresearch/PrivacyGuard/blob/main/privacy_guard/shadow_model_training/tests/test_model.py:
The first 16 lines of 'privacy_guard/shadow_model_training/tests/test_model.py' do not contain the patterns:
	Copyright
https://github.com/facebookresearch/PrivacyGuard/blob/main/privacy_guard/shadow_model_training/tests/test_training.py:
The first 16 lines of 'privacy_guard/shadow_model_training/tests/test_training.py' do not contain the patterns:
	Copyright
```

 ---
Session: DEV42745488

Reviewed By: lucamelis

Differential Revision: D91036757

fbshipit-source-id: a77d1fbb1ab7b6ee741cd6c0def0203b2eddcb4c

Author: mgrange1998

privacy_guard/shadow_model_training/dataset.py

@@ -1,4 +1,13 @@
-# (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 # pyre-strict
 """

privacy_guard/shadow_model_training/model.py

@@ -1,4 +1,13 @@
-# (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 # pyre-strict
 """

privacy_guard/shadow_model_training/tests/test_dataset.py

@@ -1,4 +1,13 @@
-# (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 # pyre-strict
 """

privacy_guard/shadow_model_training/tests/test_model.py

@@ -1,4 +1,13 @@
-# (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 # pyre-strict
 """

privacy_guard/shadow_model_training/tests/test_training.py

@@ -1,4 +1,13 @@
-# (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 # pyre-strict
 """

privacy_guard/shadow_model_training/training.py

@@ -1,4 +1,13 @@
-# (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 # pyre-strict
 """

privacy_guard/shadow_model_training/visualization.py

@@ -1,4 +1,13 @@
-# (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 # pyre-strict
 """