[!!!][TASK] Remove css_styled_content

Remove the css_styled_content extension and every connected
file. Also adapt current documentation comments to fluid_styled_content.

Releases: master
Resolves: #80876
Change-Id: I7ff65bc401ce178b9565935dba7142c6dd8f414f
Reviewed-on: https://review.typo3.org/52476


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Thomas Hohn <thomas@hohn.dk>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Benjamin Kott <benjamin.kott@outlook.com>
Tested-by: Benjamin Kott <benjamin.kott@outlook.com>