[FEATURE] Add LogManagerInterface

The interface \TYPO3\CMS\Core\Log\LogManagerInterface enables you
to ship an alternative 3rd party LogManager instance.
Having dependency injection in place, you could replace the core
Logger without touching a single line of code.

Releases: 6.3
Resolves: #60551
Change-Id: I2bf125f93599dee9a08e6c6b6fa7c369a7680d8d
Reviewed-on: http://review.typo3.org/31791
Reviewed-by: Sascha Egerer <sascha@sascha-egerer.de>
Tested-by: Sascha Egerer <sascha@sascha-egerer.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>