[TASK] Move classAliasMaps into compatibility6 extension part 3

This is the sysext:css_styled_content class alias part

Change-Id: I891b3717b34858498d2394c385709326c5816558
Resolves: #62613
Related: #62013
Releases: master
Reviewed-on: http://review.typo3.org/33701
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Frank Nägler <typo3@naegler.net>
Tested-by: Frank Nägler <typo3@naegler.net>
Reviewed-by: Alexander Opitz <opitz.alexander@googlemail.com>
Tested-by: Alexander Opitz <opitz.alexander@googlemail.com>