[TASK] Deprecate Extbase CommandControllers and @cli annotation

Back then, the PHPDoc annotation `@cli` was added to indicate
Extbase CommandController commands to be usable on CLI only
instead of also be usable as a scheduler task.

The concept of Extbase Command Controllers has been superseded
with symfony/console and its integration into TYPO3 CLI in TYPO3 v8.0,
and contains all features necessary to build commands of any kind
of complexity.

As a matter of documentation, it is however crucial to document
how to instantiate Extbase from CLI to migrate easily from Extbase CLI
to symfony/console.

Releases: master
Resolves: #85977
Change-Id: Id87c2ce300e01bf649bd1c2219aa17b8437bda83
Reviewed-on: https://review.typo3.org/58064


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Frans Saris <franssaris@gmail.com>
Tested-by: Frans Saris <franssaris@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>