[TASK] Allow modals to stay open after invoking an action

A new enum `PostActionModalBehavior` is added to allow control whether
a modal window should stay open after invoking either an
`ImmediateAction` or `DeferredAction`.

Such action may return any value of `PostActionModalBehavior`, namely
`KEEP_OPEN` or `CLOSE`. If nothing is provided, the default behavior is
to close the modal.

Resolves: #99189
Releases: main
Change-Id: Ie309122e0f2b197f317b2db13dbbc1f7e2c17a70
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76818


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>