[TASK] Migrate BackendWorkspaceRestriction to Context API

This patch also streamlines the Context API usage of
Workspaces in the main AbstractDataHandlerActionTestCase
class.

Resolves: #86465
Releases: master
Change-Id: I99e2a379e745494f9c23cca40ca4ad7ee1fc887f
Reviewed-on: https://review.typo3.org/58484


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>