v2: major revamp of the structure of the cli.

[shivamhwp]

1. rather than using model's respective api's, move to openrouter using openrouter-rs crate, thanks to @realmorrisliu.
2. literally use any model available on openrouter. (run git-acm get-models -> models stored in ~/.config/git-acm/models.json -> use any of em. ).
3. some more stuff, idk right now.

[shivamhwp]

it's ready !!