[!!!][TASK] Replace ExtJS DateTimePicker with bootstrap alternative

Follow-up: only deprecate unused method, not remove.

Resolves: #62925
Releases: master
Change-Id: Icce2e9756d74c1c3297fd57e125f67c27056b087
Reviewed-on: http://review.typo3.org/35580
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>