[TASK] Introduce ColumnMap\Relation enum

This patch introduces ColumnMap\Relation enum as a
replacement for the former ColumnMap::RELATION_*
class constants.

Releases: main
Resolves: #100272
Change-Id: I517bd3ed30815e1bc51845ae2739121999ca5863
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78230


Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Nikita Hovratov <nikita.h@live.de>