[FEATURE] Display loading mask in Extension Manager

Add a loading mask effect, whenever the User has clicked
on one of the two buttons of the compatibility check message
in the Extension Manager.

Resolves: #59498
Releases: 6.2
Change-Id: I5aed3bb5ffc4b2f0b490ec3da608b9cf33d22d06
Reviewed-on: https://review.typo3.org/30664
Reviewed-by: Fabien Udriot
Reviewed-by: Marcin Sągol
Reviewed-by: Nicole Cordes
Tested-by: Nicole Cordes
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers