EZP-20069 - Expose SignalSlot repository properly, via a service tag
EZP-20069 - Moved legacy related slots definition to LegacyBundle
EZP-20069 - Implemented a generic slot that converts signals to a Symfony event
EZP-20069 - Added unit tests
EZP-20069 - Added test for SignalSlotPass
EZP-20069 - Added phpDoc

[ci skip]
Merge pull request #440 from ezsystems/signalSlotExposed

EZP-20069: Expose SignalSlot repository properly