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/util/Cargo.toml

@@ -18,7 +18,7 @@ test-support = ["tempfile", "git2"]
 [dependencies]
 anyhow.workspace = true
 collections.workspace = true
-dirs = "3.0"
+dirs.workspace = true
 futures.workspace = true
 git2 = { workspace = true, optional = true }
 globset.workspace = true