feature: allow to close document from buffer picker

[yo-main]

Allow to close an opened buffer using the DEL key while inside the buffer picker.

This is something that I have been missing: it's a bit annoying to open and manually close each buffer I want to close from the buffer picker.

There's probably a better way to implement this. Happy to get some directions if that is the case.

[Aaalibaba42]

The CloseError::SaveError contains an anyhow::Error with potentially useful information that gets discarded.

Suggested change

	CloseError::BufferModified(s) => format!("Could not close modified buffer: {}", s),
	_ => "Could not close buffer".to_owned(),
	CloseError::BufferModified(s) => format!("Could not close modified buffer: {}", s),
	CloseError::SaveError(e) => format!("Could not close buffer: {}", e),
	CloseError::DoesNotExist => "Buffer does not exist".to_owned(),

[Aaalibaba42]

I don't think this should be included in the worktree, you should be able to upload to github directly on the PR itself as a file attached to a comment.

[Aaalibaba42]

On some keyboards (Mac for instance), there's typically only a Backspace key. Consider also binding something more portable, I don't really know what's the standard in the rest of the codebase (I can see ctrl!('d') in some places but not sure what's the "standard").

[yo-main]

I've set an alternative with alt('d') as ctrl!('d') is already in the picker

[Aaalibaba42]

You could add a few integration tests, I've found commands/write.rs:131-160 and splits.rs:6-70 that you could take inspiration from to make your own integration test.

The feature seems to be working well though, it's useful and I think reasonable to add to core instead of a plugin.

(I'm just a contributor trying to help review things as they come in to make it easier for maintainers when they get here, don't take my word authoritatively)