[TASK] Rework DataHandler->doesBranchExist

This change adapts DataHandler->doesBranchExist
to work with an array instead of a stringlist
and the magic "-1" value.

In addition, related internal methods also now
use proper PHP native types.

Resolves: #102563
Releases: main
Change-Id: Ic44b1bde0e771c798d0512a518a0293e4ded6209
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82009


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Andreas Kienast <a.fernandez@scripting-base.de>