feat(TrainingCancellation): enhance cancellation functionality and localization support

- Updated the training cancellation controller to accept training group IDs, improving the cancellation process.
- Modified the database schema to include a JSON field for training group IDs in the training cancellations table.
- Enhanced the TrainingCancellation model to support the new training group IDs field.
- Updated the training cancellation service to normalize and handle training group IDs effectively.
- Added localization support for training cancellation features across multiple languages, improving user experience.

backend/migrations/add_training_group_ids_to_training_cancellations.sql

@@ -0,0 +1,2 @@
+ALTER TABLE training_cancellations
+  ADD COLUMN IF NOT EXISTS training_group_ids JSON NULL;

backend/migrations/create_training_cancellations_table.sql

@@ -5,6 +5,7 @@ CREATE TABLE IF NOT EXISTS training_cancellations (
   end_date DATE NOT NULL,
   date DATE NULL,
   reason VARCHAR(255) NULL,
+  training_group_ids JSON NULL,
   created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
   updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
   UNIQUE KEY uniq_training_cancellation_club_range (club_id, start_date, end_date),