Tests Failing due to SSL verification error.

[pctablet505]

Issue Summary: SSL Certificate Failures in AutoKeras Tests

Problem
AutoKeras tests are failing due to SSL certificate verification errors when downloading datasets and pre-trained model weights from Google Cloud Storage URLs.

Failing Tests

test_structured_data_infer_col_types - Titanic dataset download
test_resnet_pretrained_build_return_tensor - ResNet50 weights
test_resnet_pretrained_with_one_channel_input - ResNet50 weights
test_xception_pretrained_build_return_tensor - Xception weights
test_xception_pretrained_with_one_channel_input - Xception weights
test_greedy_oracle_populate_doesnt_crash_with_init_hps - EfficientNet weights
Root Cause
[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate

Proposed Solution

Replace network downloads with pre-bundled local files:

Add titanic_train.csv and titanic_test.csv
Add models directory with ResNet50, Xception, and EfficientNet weights
Modify test_utils.py to use local paths instead of downloads
Impact
All tests pass offline without network dependencies or SSL workarounds.

[pctablet505]

@haifeng-jin

For these failures, do you have any suggestions.
We can have local models, or might need to deal with SSL verification.