Tyr: convert to threaded IRQs as appropriate

Panthor mostly uses threaded IRQs.

The abstractions for this are already available, so we should follow suit in Tyr.

Please convert all the IRQ handlers to threaded IRQs. Also implement the code for _suspend and _resume while at it.

changed milestone to %Tyr (i.e.: the Rust port of Panthor)

added Backlog label

added tyr label

This will apparently be needed for the scheduler code, so I am taking it.

assigned to @dwlsalmeida