[FEATURE] Use TCA/Overrides for TCA changes

Move customization of existing TCA structures into
the TCA/Overrides folder.

Resolves: #59047
Releases: 0.6
Change-Id: I5a042aaee743b5ff0045dbf9006a2a08451a6a1e
Reviewed-on: https://review.typo3.org/30345
Reviewed-by: Francois Suter
Tested-by: Francois Suter