[TASK] Protect tstemplate extension

The patch disentangles the tstemplate extension controller
classes. The main controller class no longer extends
BaseScriptClass and the sub controllers no longer extend
AbstractFunctionModule. The classes set as many properties
and methods to protected to allow further refactoring of this
module in v10.

Resolves: #86207
Releases: master
Change-Id: If9ad462a423be5f0e370e0894ebb848b822ee66b
Reviewed-on: https://review.typo3.org/58240


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>