Add implicit runner inside Reflector

[clux]

To avoid people having to do this type of task spawning just to ensure a reflector is up to date:

https://github.com/babylonhealth/shipcat/blob/fd78055e795017b276eb99de3ecc86a2f99eab86/raftcat/src/state.rs#L184-L207

There's no reason why people NEED to do this themselves. It should be encapsulated herein if possible.

This should also be integrated with signal handlers in the future. But making a separate issue for that.