feat: Add filter_keybinding to KeyBindingRegistry

[lucyleeow]

closes #206

Adds a filter_keybinding (not 100% on name) attr to KeyBindingRegistry, which takes Callable[[KeyBinding], str] - if str is empty the keybinding is valid otherwise error message str should be returned.

Just a start, happy to take any feedback.

Will update docs once code ready.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (0e801a9) to head (645062c).
Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #212   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           31        31           
  Lines         1814      1833   +19     
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+ Hits          1814      1833   +19     

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[tlambert03]

looks good, but we need to catch the new possible ValueError inside of the for loop in register_action_keybindings

            if d := self.register_keybinding_rule(action.id, _keyb):
                disposers.append(d)

otherwise one bad keybinding will ruin the whole batch (and add a test for that)

[lucyleeow]

Thanks @tlambert03, I think changes are made. I will look at any doc updates once code okay.

[tlambert03]

thanks @lucyleeow, perfect 👌