[TASK] Block access to .typoscript files

As .typoscript is the preferred file ending for TypoScript files,
this should be reflected in the .htaccess access rules as well.

Change-Id: If894d831afb5fd7e3ed1c098023111b82cde124f
Resolves: #83703
Releases: 7.6
Reviewed-on: https://review.typo3.org/55626


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Reiner Teubner <rteubner@me.com>
Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>