feat: Integrate rclone command functionality into configuration management

- Added support for selecting rclone commands and their associated flags in the configuration form.
- Implemented backend logic to handle rclone command retrieval and flag management.
- Enhanced the database schema to include rclone command and flag fields in the transfer configuration.
- Created new migration scripts to add rclone-related tables and fields.
- Updated the scheduler to execute transfers using the selected rclone command and flags.
- Developed new handlers for rendering rclone command options and flags in the web interface.
- Improved error handling and logging for rclone command execution and configuration updates.

internal/db/migrations/migrations.go

@@ -19,6 +19,8 @@ func GetMigrations(db *gorm.DB) *gormigrate.Gormigrate {
 		AddTimestampsToJobHistories(), // 006
 		AddNotificationServices(),     // 007
 		AddUserNotifications(),        // 008
+		AddRcloneTables(),             // 009
+		AddRcloneCommandToConfig(),    // 010
 	)
 
 	return gormigrate.New(db, gormigrate.DefaultOptions, migrations)