Add KDocs to Kotlin bindings from webgpu.json.

This change leverages the existing API documentation found in
`webgpu.json` and adds it into the generated `*.kt` files.

Key Changes:
- Modifying `dawn_json_generator.py` to load and parse the `webgpu.json` file.
- Created dawn_yaml_utility.py to add common utility functions
- Updating the `art_kotlin_enum` template to read the parsed documentation and use it as KDocs.

Change-Id: Ia7061962ea926a04f6d788ad16f2992791b0f7ed
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/264874
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Loko Kung <lokokung@google.com>
Reviewed-by: Jim Blackler <jimblackler@google.com>