[TASK] Visual tweaks of "Workspaces" backend module

- Record table list is responsive on small screens
- Nested records are indented

Resolves: #75720
Releases: master
Change-Id: If64ea18126581249c1b47891de74beec0128b998
Reviewed-on: https://review.typo3.org/47735


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Susanne Moog <typo3@susannemoog.de>
Tested-by: Susanne Moog <typo3@susannemoog.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>