Extract paths out of util (#13182)

This PR extracts the definition of the various Zed paths out of `util`
and into a new `paths` crate.

`util` is for generic utils, while these paths are Zed-specific. For
instance, `gpui` depends on `util`, and it shouldn't have knowledge of
these paths, since they are only used by Zed.

Release Notes:

- N/A

crates/settings/src/settings_file.rs

@@ -4,7 +4,7 @@ use fs::Fs;
 use futures::{channel::mpsc, StreamExt};
 use gpui::{AppContext, BackgroundExecutor, UpdateGlobal};
 use std::{io::ErrorKind, path::PathBuf, sync::Arc, time::Duration};
-use util::{paths, ResultExt};
+use util::ResultExt;
 
 pub const EMPTY_THEME_NAME: &str = "empty-theme";