* feat: detach dedicated exec jobs
* feat: async `DedicatedExecutor::join`
Now `DedicatedExecutor` follows the system we use for other server
components:
- `shutdown`: a quick sync call that signals the shutdown but doesn't
drop
- `join`: async awaits until the executor has finished shutdown
- `drop`: warn but still try to shut down
* test: irmpove `detach_receiver` test
Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>
Marco Neumann