[FEATURE] Add hook for content element footer in Page module

Currently, there is only a hook for the `tt_content_drawItem` function
in the PageLayoutView. Since 6.0 the info fields for a tt_content element
(hidden,starttime,endtime,fe_group,spaceBefore,spaceAfter) are rendered
in a footer, so there is no way to alter the rendering of the info
fields or add information to the footer.

This change adds a hook to the `tt_content_drawFooter` function
responsible for rendering the footer.

Resolves: #58929
Releases: master
Change-Id: I23c54eefd3a511fddd480b4bf08d6a3977757973
Reviewed-on: http://review.typo3.org/31309
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Frank Nägler <typo3@naegler.net>
Tested-by: Frank Nägler <typo3@naegler.net>