Open up role-based scheduling restriction

Currently users can only be scheduled to specific roles they are assigned to.

Good to have the assigned roles, but it's too limiting when it comes to scheduling.

For example, a guitarist can only be scheduled as a guitarist. For a given Sunday, they may also be asked to do the opening prayer. Unless this person has been assigned the opening prayer role, he can't be scheduled in the system.

Ideally, everyone's name is searchable for all roles, regardless of roles assigned to their specific account making it more flexible when scheduling.