Create parent directories for Windows container image (#313)

Most container runtimes, including containerd and Moby (aka Docker) with Linux images
will accept tar files where directory entries are missing.

```
-rwxr-xr-x 0/0             117 1970-01-01 01:00 app/bb_storage.repo_mapping
-rwxr-xr-x 0/0        49701048 1970-01-01 01:00 app/bb_storage
hrwxr-xr-x 0/0               0 1970-01-01 01:00 app/bb_storage.runfiles/_repo_mapping link to app/bb_storage.repo_mapping
hrwxr-xr-x 0/0               0 1970-01-01 01:00 app/bb_storage.runfiles/_main/cmd/bb_storage/bb_storage_/bb_storage link to app/bb_storage
```

If a file like `app/bb_storage.repo_mapping` is extracted, any missing parent directories are created during extraction (but before the file is created): https://github.com/containerd/containerd/blob/dea7da592f5d1d2b7755e3a161be07f43fad8f75/pkg/archive/tar.go#L268-L276

On Windows (at least with Moby), missing parent directories are never created: https://github.com/microsoft/hcsshim/blob/d97b376c86e77d0df1b94500350fd2625c516dbf/internal/wclayer/legacy.go#L694
For that reason we explicitly create those directories on Windows:

```
drwxr-xr-x 0/0               0 1970-01-01 01:00 app/
-rwxr-xr-x 0/0             117 1970-01-01 01:00 app/bb_storage.exe.repo_mapping
-rwxr-xr-x 0/0        50391552 1970-01-01 01:00 app/bb_storage.exe
drwxr-xr-x 0/0               0 1970-01-01 01:00 app/bb_storage.exe.runfiles/
hrwxr-xr-x 0/0               0 1970-01-01 01:00 app/bb_storage.exe.runfiles/_repo_mapping link to app/bb_storage.exe.repo_mapping
drwxr-xr-x 0/0               0 1970-01-01 01:00 app/bb_storage.exe.runfiles/_main/
drwxr-xr-x 0/0               0 1970-01-01 01:00 app/bb_storage.exe.runfiles/_main/cmd/
drwxr-xr-x 0/0               0 1970-01-01 01:00 app/bb_storage.exe.runfiles/_main/cmd/bb_storage/
drwxr-xr-x 0/0               0 1970-01-01 01:00 app/bb_storage.exe.runfiles/_main/cmd/bb_storage/bb_storage_/
hrwxr-xr-x 0/0               0 1970-01-01 01:00
app/bb_storage.exe.runfiles/_main/cmd/bb_storage/bb_storage_/bb_storage.exe
link to app/bb_storage.extracted
```

Note that it is generally better NOT to create parent directories, since any directories created in upper layers (like `/app` here) shadow potential directory contents of lower layers.
Long term, we should probably fix tar extraction on Windows upstream.

Author: malt3

tools/container.bzl

@@ -20,6 +20,14 @@ def multiarch_go_image(name, binary):
             "@rules_go//go/platform:linux": {"app/" + binary_name: binary},
             "@rules_go//go/platform:windows": {"app/{}.exe".format(binary_name): binary},
         }),
+        # Creating parent directories is not recommended
+        # as the directory creation during layer extraction shadows layers
+        # from parent directories instead of merging their contents.
+        # On Windows, the extraction routine requires parent directories to exist.
+        create_parent_directories = select({
+            "@rules_go//go/platform:linux": "disabled",
+            "@rules_go//go/platform:windows": "enabled",
+        }),
         # Don't build un-transitioned images, as the default target
         # architecture might be unsupported For example when building on
         # linux-i386.