[TASK] Create CSS Styled Content TypoScript configuration for 6.1

For backwards compatibility we keep versions of the CSS Styled
Content TypoScript configuration files selectable as rendering
template.

The current setup.txt and constants.txt are just copied into
the 6.1 folder. After this change the branches may diverge.

Change-Id: Ieb02fddd7de4ee41a8b91bbf5a1dd583257de13d
Resolves: #47717
Releases: 6.2
Reviewed-on: https://review.typo3.org/20332
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn