feat: introduce diagnostics context and prompt

[gennaro-tedesco]

I often find myself wanting to resolve the code diagnostics and manually adding the corresponding error messages and/or buffers to the chat, together with a custom prompt. I thought I could propose to add diagnostics as default context and prompt that the user can select in order to streamline this process.

This PR introduces:

• context: workspace diagnostics for all open buffers
• prompts: instructions for the model to patch each single one independently

[deathbeam]

tools branch already has diagnostics as separate function, and also for opened buffers. This PR is also adding diagnostics for current buffer only and not workspace diagnostics, check vim.diagnostic.get() documentation

[gennaro-tedesco]

Good morning and thank you for reviewing the PR!

For me to better understand: you are saying there is a tools branch that already superseds these changes?

[deathbeam]

Yea pretty much

[gennaro-tedesco]

Ah, very well, then we can close this PR I guess.

P. S. I don't see the tools branch (I wanted to install it) - is it the canary branch or which one?

[jellydn]

That's on open PRs on this repo @gennaro-tedesco, fyi.

[gennaro-tedesco]

Fantastic, thank you for the great work! I will close this PR.