[TASK] Increase code coverage of SignalSlot/Dispatcher

Added some missing tests to achieve 100% code coverage.
Also adjusted the copyright header and author annotations.

Releases: 6.1
Resolves: #44611
Change-Id: I9ffb474b5cd44d30c9eff49ae37ab55f5f68a5ce
Reviewed-on: https://review.typo3.org/17580
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Alexander Schnitzler
Tested-by: Alexander Schnitzler
[TASK] Increase code coverage of Service/TypeHandlingService

Added one missing tests to achieve 100% code coverage.
Also adjusted the copyright header.

Releases: 6.1
Resolves: #44612
Change-Id: If543b055c139d63edcb8960e7e0f89875017bdf3
Reviewed-on: https://review.typo3.org/17581
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Alexander Schnitzler
Tested-by: Alexander Schnitzler