[FEATURE] Introduce cObject for Extbase plugins

A new TypoScript cObject "EXTBASEPLUGIN" is
added for Extbase plugins to allow
Extbase authors to not reference the Extbase
Bootstrap class anymore. This way, newcomers
do not have to worry about running defining
USER/USER_INT things, which is not relevant
for them.

As most existing users use the API, it does not
matter much, except for places.

In the future, Extbase logic can / should
be moved to the Extbase Plugin Content Object,
while removing the dependency on the
ConfigurationManager and the cacheable actions
from the Bootstrap and RequestBuilder classes.

At the current point, this is very much convenience
and helps to further document to distinguish
between Plugins (= PHP code) and regular Content Types.

Resolves: #100293
Releases: main
Change-Id: Ia3a7cceddd9f93dc606c3194828d26bed5a8f2b2
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76517


Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Jochen <rothjochen@gmail.com>
Tested-by: Jochen <rothjochen@gmail.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>