[TASK] Use DI in styleguide field generators

* Inject service dependencies
* Clean up doc headers
* generate() can return string|int over string only
  to create better typed DB values up front
* Various further minor type improvements
* readonly classes where possible

Resolves: #104336
Releases: main
Change-Id: I2cda858d30b70d527f4024bce8c3e95b6176679e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/85146


Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Mogens Fiebrandt <mogens.fiebrandt@googlemail.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>