[TASK] RTE: Migrate to RequireJS

Releases: master
Resolves: #63636

Change-Id: Id44a8313fede29e9efe0eb2efb9142798852e4f0
Reviewed-on: http://review.typo3.org/35131
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>