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/rustdoc/src/store.rs

@@ -12,8 +12,8 @@ use gpui::{AppContext, BackgroundExecutor, Global, ReadGlobal, Task, UpdateGloba
 use heed::types::SerdeBincode;
 use heed::Database;
 use parking_lot::RwLock;
+use paths::SUPPORT_DIR;
 use serde::{Deserialize, Serialize};
-use util::paths::SUPPORT_DIR;
 use util::ResultExt;
 
 use crate::indexer::{RustdocIndexer, RustdocProvider};