[TASK] Move template for FormEngine

Moves the html template for FormEngine
from typo3/templates to EXT: backend.

Change-Id: Idcc7c45790f71ed91d83836821dba52baf9615d0
Fixes: #47893
Releases: 6.2
Reviewed-on: https://review.typo3.org/20472
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Benjamin Mack
Tested-by: Benjamin Mack