Refactor deletion (#28610)

Introduce the new generic deletion methods
- `func DeleteByID[T any](ctx context.Context, id int64) (int64, error)`
- `func DeleteByIDs[T any](ctx context.Context, ids ...int64) error`
- `func Delete[T any](ctx context.Context, opts FindOptions) (int64,
error)`

So, we no longer need any specific deletion method and can just use
the generic ones instead.

Replacement of #28450

Closes #28450

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

services/user/delete.go

@@ -185,7 +185,7 @@ func deleteUser(ctx context.Context, u *user_model.User, purge bool) (err error)
 	}
 	// ***** END: ExternalLoginUser *****
 
-	if _, err = db.DeleteByID(ctx, u.ID, new(user_model.User)); err != nil {
+	if _, err = db.DeleteByID[user_model.User](ctx, u.ID); err != nil {
 		return fmt.Errorf("delete: %w", err)
 	}