Configurable Keybinds

### Describe the feature or problem you'd like to solve

I'd like the ability to configure keybindings, to override or add to the existing keybinds.

### Proposed solution

This feature would allow CLI users to use the keybinds that make the most sense to them, particularly so that it can match similar keybinds in other applications they use. For example, I generally prefer ctrl+backspace for deleting the previous word as I do in my text editors and IDEs, rather than ctrl+w which I associate with closing a window/tab. I imagine this would just be part of the config file at ~/.copilot/config.json.

### Example prompts or workflows

_No response_

### Additional context

_No response_