[BUGFIX] Re-add dbal extension manager message class

The MessageDisplay class that is used to display a hint in the extension
settings of the dbal extension was removed with commit
2e3c9d5e25e5beadafebca949de3e05eeb6f120a.

This commit re-adds the class to prevent a PHP error.

Resolves: #52167
Releases: 6.2
Change-Id: I1fa8749ffb93eab45646948ff336bf3d331aa92c
Reviewed-on: https://review.typo3.org/23949
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn