Remove inconsistent requirement from FilterByAbility/SN that a person be selected

All the core FilterGroupsBy checkin actions process the entire family, except for FilterByAbilityLevel and FilterBySpecialNeeds.  Those two actions require a person to be selected.

We run these actions after you select a family, but before you select the person, so it doesn't do anything in our workflow.   

Core actions:
https://github.com/SparkDevNetwork/Rock/blob/develop/Rock/Workflow/Action/CheckIn/FilterGroupsByAge.cs#L60
https://github.com/SparkDevNetwork/Rock/blob/develop/Rock/Workflow/Action/CheckIn/FilterGroupsByGrade.cs#L60