feat: Support Copilot CLI (`copilot --acp`)

[ras0q]

Thank you for developing the useful plugin!

Copilot CLI has ACP support.
https://docs.github.com/en/copilot/reference/copilot-cli-reference/acp-server

It would be great if Copilot CLI were available in agentic.nvim.

[carlos-algms]

Thank you for the request. I'm glad you're enjoying the plugin.

Copilot support is on the radar.

• There's this PR: feat: Add Copilot support #102
• And this discussion: copilot cli #143

However, copilot is not feature complete, there are some blockers on their side before we integrate it.