feat(ui): inline edit preview

[Xuyuanp]

Related Xuyuanp/nes.nvim#6

Close #29

[tris203]

i seem to still be getting larger diffs on this branch, would you not expect this diff to be more minimal?

[Xuyuanp]

From what I've seen, Copilot currently seems to only return whole-line edits (like insert, delete, replace), not the real inline edits. But the structure returned by copilotInlineEdit itself can support inline edits. It's possible that the copilot will start send inline edits in the future. This PR handles it. What I am not sure about is whether we need to convert the single-line editing to inline editing.

At the same time, I am also refactoring my plugin (nes.nvim) to implement the copilotInlineEdit method and support inline edits

[tris203]

if we have removed the UI tests, then we need to also remove the screenshots from the folder