* [EC-654] Add CreateGroupCommand and UpdateGroupCommand
Added new CQRS commands CreateGroupCommand and UpdateGroupCommand Updated GroupService to use new commands
Edited existing GroupServiceTests and added new tests for the new commands
* [EC-654] dotnet format
* [EC-654] Replace GroupService.SaveAsync with CreateGroup and UpdateGroup commands
* [EC-654] Add assertions to check calls on IReferenceEventService
* [EC-654] Use AssertHelper.AssertRecent for DateTime properties
* [EC-654] Extracted database reads from CreateGroupCommand and UpdateGroupCommand. Added unit tests.
* [EC-654] Changed CreateGroupCommand and UpdateGroupCommand Validate method to private
Rui Tomé