[BUGFIX] selectTree pageTsConfig addItems

Adding items for type selectTree with pageTsConfig does not
work as documented. The TCA tree needs multi-root handling
to handle that. Additionally, some slight changes in the order
of elements when items are calculated are needed.

Resolves: #78628
Releases: master
Change-Id: Iecf0225c0eeaab8ea661997cad26e68d255d8460
Reviewed-on: https://review.typo3.org/50565


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>