feat: Implement multi-configuration support for jobs

- Add support for multiple transfer configurations per job, allowing users to select one or more configurations.
- Update job creation and editing forms to handle multiple configuration selections with checkboxes.
- Enhance job processing logic to iterate through all associated configurations during execution.
- Introduce database migrations to add necessary fields for storing multiple configuration IDs.
- Update dashboard and history views to display configuration details for jobs.
- Refactor related templates and handlers to accommodate the new multi-configuration functionality.

internal/db/migrations/migrations.go

@@ -13,6 +13,7 @@ func InitMigrations(db *gorm.DB) *gormigrate.Gormigrate {
 		AddCloudStorageFields(),
 		AddSkipProcessedFilesColumn(),
 		AddMaxConcurrentTransfersColumn(),
+		AddMultiConfigSupport(),
 	}
 
 	return gormigrate.New(db, gormigrate.DefaultOptions, migrations)