Add AppLogger

[rullzer]

Add a Logger implementation to the AppContainer that is a simple wrapper around the default logger.
But this has always the app context set. So we can more easily track where log messages and exception come from.

[nextcloud-bot]

GitMate.io thinks possibly related issues are #10255 (Add support for room shares), #363 (Add Snap Information), #3801 (Adding appointment into shared calendar fails), #8098 (Adding new user fails), and #5788 (add catalan language again).