Draft: Issue #3543794: Fix image style generation for filenames with multiple dots
- Add ImageFactory service injection to StageFileProxySubscriber
- Use ImageFactory::getSupportedExtensions() to validate unconverted file extensions
- Improve file extension detection for image style conversion
- Fix use_imagecache_root logic to properly handle original image fetching
This change resolves issues where image derivatives were not being properly generated for files containing multiple dots in their filenames. The ImageFactory service is now properly injected and used to validate supported image extensions, ensuring that the unconverted path logic works correctly with the use_imagecache_root configuration setting.
Closes #3543794