[FEATURE] Add File picker in TYPO3 Backend

The patch adds / replaces the old file picker when clicking
on button "add image". It has a User TSconfig for controlling
the behaviour.

mod.media.enableMediaFilePicker = 1

Change-Id: Icb2f0c2a7673ca240da944f52fb34c0ea65a616d
Releases: 2.0.0
Resolves: #50810
Reviewed-on: https://review.typo3.org/25254
Tested-by: Alexander Pankow
Reviewed-by: Fabien Udriot
Tested-by: Fabien Udriot