[FEATURE] Add PSR-14 event to control hreflang tags to be rendered

A PSR-14 event is introduced to make it possible to control the
hreflang tags that will be rendered.

Additionally the class HrefLangGenerator is migrated to be a
listener to the new event.

Resolves: #86614
Releases: master
Change-Id: I51a5a79da6996148e62301c793b0ad257aada102
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/59059


Tested-by: Richard Haeser <richard@maxserv.com>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Reviewed-by: Richard Haeser <richard@maxserv.com>
Reviewed-by: Susanne Moog <look@susi.dev>