Fix fileprovider name

[YapWC]

Exposed the bundle_indentifier in cookiecutter and updated the AndroidManifest, replacing {{ cookiecutter.bundle }}.{{ cookiecutter.app_name }} with {{ cookiecutter.bundle_identifier }}. This removes the underscore/hyphen mismatch and prevents the FileProvider “couldn’t find meta-data” crash for apps whose IDs contain underscores.

The Android manifest template currently builds the FileProvider authority from bundle + app_name, e.g. com.example.image_classification.fileprovider (with an underscore). At runtime, Toga’s Android camera code looks for the FileProvider using the hyphenated authority (com.example.image-classification.fileprovider), but the manifest has registered a different authority with an underscore.

By switching the manifest to use {{ cookiecutter.bundle_identifier }}. The authority in AndroidManifest.xml becomes com.example.image-classification.fileprovider, which matches exactly what Toga expects at runtime.

Fixes beeware/toga#3237

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[freakboy3742]

Thanks for the fix!