Support defactivity/defworkflow var derefencing for hot-reloading code without worker restarts

[thenonameguy]

Right now the handler fns are dereferenced when the worker is started.
It would be provide a less worker-restart-heavy development workflow if these vars would be deref'd at the last possible moment before execution.
Preferably with a direct-linking like flag to control the behavior.

[ghaskins]

I use integrant with integrant-repl, so reloading for me has always been a painless matter of calling (reset), but I am open to ways to make this better DX. PR's welcome

[ghaskins]

If the implementation will be non-trivial, I suggest starting with a design proposal that we can discuss.

[thenonameguy]

Great!
I use that too, just with large systems where reset isn't exactly cheap/fast.

I'll have a stab at this ticket soon. Cheers!