Add Angular config template

# Add suitable annotation config template in annotator/templates/angular.json

> ### Empty template json

```json
{
"name": "",
"exclude_dirs": [],
"exclude_files": [],
"exclude_extensions": []
}
```

- refer to existing templates in `annotator/templates/` for better idea

Compare the requested annotator/templates/angular.json with the existing templates in annotator/templates/. Use the issue's empty JSON structure as the baseline and ensure the new Angular template is valid and consistent with those examples; done means the file exists with suitable Angular annotation settings.

索引モデルが issue の本文から書いたものです。