[!!!][TASK] Replace switchable controller actions terminology

During the creation of Extbase itself, the configuration of
controllers and their available/callable actions has been called
switchable controller actions. This terminology has later also been
used to configure an alternative controller configuration defined
via typoscript or flexforms. As of today the term "switchable controller
actions" is only used for the latter. The core, however, still uses
this terminology for both the default controller configuration and
the overrides.

To clarify the terminology, the default configuration has been
renamed to just "controller configuration".

Releases: master
Resolves: #88496
Change-Id: I718e2fe03d3560a57b17fc584479aff559d105e8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60834


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Susanne Moog <look@susi.dev>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>