[TASK] Add fallback for EXT:cms label references

Make the ext:cms removal non-breaking by installing a fallback for the
label references.

Additionally remove the leftover reference to EXT:cms from the root
composer.json and replace a reference to a no longer existing path in
tsref.xml.

Resolves: #68017
Releases: master
Change-Id: Iae6a66814adce5849cef577f036010c5323d8f2f
Reviewed-on: http://review.typo3.org/41051


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>