Revise Copilot triggers. Request completion on demand

[verte-zerg]

• request completion on demand after pressing copilot_show_completion
• enable iteration over completions by pressing copilot_show_completion again
• trigger copilot completion request after inserting a new line

[AlexanderDickie]

Hi, thanks for the pr!
Ive made some refactors to my branch so that completions are now requested when the user enters insert mode, and when the document changes while in insert mode. So this new condition means a completion will now be triggered when inserting a new line and some more instances where completions weren’t previously requested (eg deleting a character, applying a regular completion).

Given this do you think it’s still necessary that copilot_show_completion will trigger a completion? Since because you’ll be in insert mode when calling this command, my refactor above will have now mean that a completion will already have been requested for the same doc state.

The completion iteration function should be added, I would also like the ability to hide a completion too, eg either have copilot_show_completion show no completion after cycling past the final completion, or include a second function which cycles backwards eg copilot_decrement_or_hide_completion?

Please feel free to make other suggestions/prs for improvements, I havent been using this branch much (I mainly use c# atm which I cant use with helix as there is no good lsp) so Im interested how you find this