[TASK] Remove usage of Asset Repository

Asset repository will not survive the table split
of sys_file_metadata and sys_file. The change-set
also removes the relations (categories, FE groups)
within the Asset object.

Change-Id: If9a2972077817893cc57c228a7cbb1054438e418
Releases: 3.0
Resolves: #60960
Reviewed-on: http://review.typo3.org/32145
Reviewed-by: Fabien Udriot <fabien.udriot@ecodev.ch>
Tested-by: Fabien Udriot <fabien.udriot@ecodev.ch>