[TASK] Add namespaing to WorkspaceService

Resolves: #47199
Releases: 6.1
Change-Id: Id7326e8766e9bd2923102ea4fe1645007b82964b
Reviewed-on: https://review.typo3.org/19949
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn