[TASK] RTE: Migrate editor textarea container to plain JavaScript

Releases: master
Resolves: #63793
Change-Id: I936ac320e375ac7e1a5827221ee528f463785d08
Reviewed-on: http://review.typo3.org/35333
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>