[BUGFIX] Module Permissions: wrong un-/lock icon state

Fix icon state by replacing unlock with locked icon.
Add better explaining tooltip text for locked pages.

Releases: master
Resolves: #71357
Change-Id: If2a0c587b4f3e9b2c4f64486a0b6464ca2e47477
Reviewed-on: https://review.typo3.org/44562


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Frank Nägler <frank.naegler@typo3.org>
Tested-by: Frank Nägler <frank.naegler@typo3.org>