Prevent possible deadlocks when pressing Escape to cancel recordings

[dannysmith]

So #224 allows the Escape key to be used to cancel recording. My #401 basically implemented this in a similar (though more generic way) before 224 was merged. Looking at this commit in 401, I think the only thing worth keeping from my implementation is this...

Problem

In toggle mode (non-push-to-talk), the shortcut callback holds the ManagedToggleState
lock while calling action.start() or action.stop(). If the action needs to acquire the
same lock (e.g., cancel_current_operation resets toggle states), this causes a
deadlock.

Solution

Release the lock before calling the action:

let should_start: bool;
{
    let mut states = toggle_state_manager.lock()...;
    should_start = !*is_currently_active;
    *is_currently_active = should_start;
} // Lock released

if should_start { action.start(...) } else { action.stop(...) }

Steps after this PR is merged

• Refactor Add support for fn key and Escape to cancel on macOS #401 to remove escape (even though it'll probably not get merged, I'm using it in my fork until we have a better way of handling fn key on macOS)

@cjpais If you'd prefer the slightly more generic approach to handling dynamic keybindings in 2915aea I can also add that to this PR too.

[cjpais]

I really liked the dynamic keybindings bit when I reviewed from what I recall if you could bring that refactor in too it would be great. I think it starts to set us up a lot better for moving to letting users define all kinds of keybindings if they want

[dannysmith]

#224 includes dynaming keybinding already, but not in an easily reusable way. I'll bring that stuff over into here from #401 because yeah - I agree. Will ping you when I ned a review

[cjpais]

I had claude port over the dynamic bindings, I haven't reviewed honestly. It does work from my brief testing, but would be helpful to have your review as well. I will take a closer look at the code itself when I can. If I just messed things up, feel free to revert the changes

[cjpais]

Im running into some issues while testing the dynamic part. I think maybe it would be a nice thing to bring in but I'd rather bring in the fix now rather than later so I'm going to revert to your merge, re-merge, test and pull in

[jacksongoode]

Thanks for the PR! This implementation definitely catches a major flaw.