[BUGFIX] RTE: Support anchors without `href`

Removes enforcing of href attribute when storing RTE text into the
database. Removes adding of absolute scheme on a tags without href
attribute, when loading text from the database. Changes
ContentObjectRenderer::typolink to render a tag without href anyway, if
id or name attribute is present.
Adds unit tests.

Resolves: #87992
Releases: master, 9.5
Change-Id: I4dcd33e6f13dc6a1f364c96b425aa2f241653ae9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60324


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Tested-by: Guido Schmechel <guido.schmechel@brandung.de>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Susanne Moog <look@susi.dev>
Reviewed-by: Guido Schmechel <guido.schmechel@brandung.de>
Reviewed-by: Benni Mack <benni@typo3.org>