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/client/src/client.rs

@@ -509,7 +509,7 @@ impl Client {
         let credentials_provider: Arc<dyn CredentialsProvider + Send + Sync + 'static> =
             if use_zed_development_auth {
                 Arc::new(DevelopmentCredentialsProvider {
-                    path: util::paths::CONFIG_DIR.join("development_auth"),
+                    path: paths::CONFIG_DIR.join("development_auth"),
                 })
             } else {
                 Arc::new(KeychainCredentialsProvider)