[FEATURE] Reuse existing index

Add the possibility to refer to an existing index
for column configurations. This way the "ctrl" section
still has to exist, but not the columns, for which
an existing configuration is taken.

Resolves: #56152
Releases: 2.3
Change-Id: I542f469ff701717b8a188fadf173766f8e693319
Reviewed-on: https://review.typo3.org/30499
Reviewed-by: Francois Suter
Tested-by: Francois Suter