ディスク上でアセットを移動する際に呼び出されます。
If this is implemented, it allows you to move the asset yourself but do remember to return the correct enum or do some other processing and let Unity move the file The moving of the asset can be prevented by returning AssetMoveResult.FailedMove You should not call any Unity AssetDatabase api from within this callback, preferably keep to file operations or VCS apis.