Copilot-lua-cmp: change C-c mapping

[Chachi04]

Is your feature related to a problem?

Now the completion.copilot-lua-cmp maps C-c to "dismiss", however, it is a common practice to use C-c to exit form insert mode.

Describe the new feature

Use another keymap for the copilot dismiss function, e.g. C-q (for quit), or some other keymap.

Additional context

No response

[Uzaaft]

Propose an alternative in a PR. :)