[feature request] Owners and backup owners can update/resolve tasks (+ possibly superusers)

[massey21]

Can owners and backup owners (non-staff) be granted permissions to update and resolve tasks? This allows people who aren't staff but who have specific ownership over a tool to address tasks that fall outside the normal domain of the equipment maintenance staff. For example, if a user submits a ticket saying that a chemical is running low at tool_X (or to the generic "chemicals" tool), I want our non-staff chemical inventory people to be able to resolve the ticket themselves when the chemical is replenished.

Similarly, often superusers are able to respond to issues, and I would like the ability to empower them to update or resolve tasks themselves.

This request is distinct from #190, but some of the implementation details might overlap.