[TASK] Log signal dispatching to debug log

To be able to find out which signals are triggered
during requests debug logging has been implemented
in the SignalSlotDispatcher.

Related: #84044
Resolves: #84888
Releases: master
Change-Id: I2c25c51644e8294848f8f053908984d85c5a1e83
Reviewed-on: https://review.typo3.org/56822


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>