feat: Add Google Photos support for transfer configurations

- Introduce Google Photos as a source and destination option in the configuration forms.
- Implement authentication handling and configuration management for Google Photos.
- Update database schema and migrations to include new fields related to Google Photos.
- Enhance UI components to support Google Photos-specific settings and forms.
- Add tests for Google Photos integration, ensuring proper functionality and authentication flow.
- Limit concurrent transfers for Google Photos to ensure compliance with API restrictions.

internal/db/migrations/migrations.go

@@ -17,6 +17,7 @@ func InitMigrations(db *gorm.DB) *gormigrate.Gormigrate {
 		UpdateSkipProcessedFilesToNullable(),
 		AddWebhookSupport(),
 		AddGoogleDriveAuthenticated(),
+		AddGooglePhotosSupport(),
 	}
 
 	return gormigrate.New(db, gormigrate.DefaultOptions, migrations)