[TASK] Send merged slack channel message

Merged stefan.buerk requested to merge merge-messages-1 into main

This change retrieves further informations and also sends now a proper merged slack channel message to the core-dev slack channel #typo3-cms-coredev. To enrich and stay near the well known format additional gerrit change query is implemented, but guarded with some fallback up to a some feasonable level.

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