implement nested tree for media folders
move media to different folder / refactor folder move
Merge branch 'feature/move-media-15327' into feature/folder-tree

* feature/move-media-15327:
  move media to different folder / refactor folder move
  implement nested tree for media folders

Conflicts:
	Command/MigrateNameCommand.php
	Controller/FolderController.php
	Entity/Folder.php
	Form/FolderType.php
	Repository/FolderRepository.php
	UPGRADE.md