[TASK] Avoid controller methods on Fluid RenderingContext

The getter/setter methods related to controller name
and action name will be removed in Fluid 3.0.

An equally valid solution is to specify the template
path and filename, which also avoids the lookup
logic in Fluid from running and further increases the
failsafe operation of this controller.

Resolves: #89859
Releases: master
Change-Id: I8a3422681bef4b8ada043877ffa3c57eba82d8be
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62539


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Alexander Schnitzler <review.typo3.org@alexanderschnitzler.de>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Alexander Schnitzler <review.typo3.org@alexanderschnitzler.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>