Allow generation stop

[teocns]

With issue #52 we have fixed concurrent, parallel generations on <C-g>.

This command could be potentially enabled to stop generation while running;

[Robitx]

Hey, there already is a plugin wide :GpStop command with recommended shortcut <C-g>s but people can choose a different one. 🙂

I'd prefer not to put it on the same shortcut exactly because of #52 - people might hit <C-g> more times than they wanted by accident.

What might be beneficial is to set <C-g>sautomatically for chat buffers and mention it in the chat template so that people don't have to memorize it.

@teocns What do you think?

[teocns]

Yes indeed, let's add it so it's more intuitive; its absence is the main reason I opened this issue. Thank you!