[TASK] Move PageRepository to EXT:core

Since Context API was introduced in TYPO3 v9, PageRepository is highly
decoupled from $TSFE->sys_page, and fully works standalone.

It is also used in various places where TSFE is not needed,
or required, but also in places of EXT:core.

Especially parts like RootlineUtility, which depends on PageRepository
very much, cannot live without it.

I propose to move this highly important PHP class into EXT:core,
in order to allow to decouple EXT:frontend even further from
EXT:core.

The FQCN is moved from
- \TYPO3\CMS\Frontend\Page\PageRepository
to
- TYPO3\CMS\Core\Domain\Repository\PageRepository

It can be assumed to use PageRepository for any use-case
and actually reduce usages towards BackendUtility::get...
by using this API more and more.

Further adaptions could be to reduce the logic
within PageRepository and move this into QueryBuilder
and assimilate especially the "versionOL" behavior.

Resolves: #88746
Releases: master
Change-Id: Id8225100ac60bd77fc7e1303efb4c46b741d3415
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/61166


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>