[BUGFIX] Support dots in page.meta

The parsing of the meta tag TypoScript configuration does a too greedy
check on dots and hence breaks support for examples like DC.author.

Fix this by completely refactoring the meta tag generation and add unit
tests.

Resolves: #59890
Releases: 6.3, 6.2
Change-Id: Id534efff30903d96aee1677989d1bd6d3dd1644b
Reviewed-on: https://review.typo3.org/31406
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring