[TASK] Deprecate/rewrite old mail functions

Old mail functions must be either deprecated or rewritten to use the new
mail API that was introduced in 4.5. In Version the notifications for
workspace changes can use the new mail API too.

Change-Id: I42f73e278e06546ea87b506be296306f6541a936
Fixes: #47037
Related: #42321
Releases: 6.1
Reviewed-on: https://review.typo3.org/19739
Reviewed-by: Markus Klein
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind