Casa volunteer deactivate

[maebeale]

What github issue is this PR for, if any?

Resolves #230: Admins can Deactivate volunteers from Volunteer Edit
Depends on casa-cases-unassign PR

What changed, and why?

• Added deactivate endpoint/route
• Add active_volunteer method on user to indicate if volunteer is active
  • Wanted a DRY approach to determining if the volunteer's current role is 'volunteer' (vs 'inactive')
  • Naming this is_active isn't quite right bc they might be an active Supervisor, CasaAdmin, etc. Don't love calling @volunteer.active_volunteer, but, seems needed here bc of volunteer/user obfuscation
• Changed Actions column on Assigned Cases section to only show if volunteer active
• Changed "Assign Volunteer" button to secondary so there's only one primary on the page
• Conditionally displaying Add Cases section only if volunteer is active
• Change casa_case edit volunteer_assignment to differentiate between having been unassigned vs deactivated

Notes

• Would prefer not to have to add both get and patch here. Any advice?

How will this affect user permissions?

• Volunteer permissions:
• Supervisor permissions:
• Admin permissions: Admins can Deactivate volunteers from Volunteer Edit

How is this tested? (please write tests!) 💖💪

• Help, please!

Screenshots please :)

[compwron]

It looks great! Thanks :) :) ✨🚀