Add missing pieces to AndroidContentXXXX

There are quite a few missing pieces from AndroidContentFileEngine:

• create a new file into an existing folder URI.
• create a new folder into an existing folder URI.
• remove a file/folder.
• rename a file/folder.
• move a file/folder to another place.
• copy a file/folder to another place.

We'll have to check if all the needed feaures are available in QAbstractFileEngine & co.