paths: Replace lazy_static! with OnceLock (#13213)

This PR replaces the `lazy_static!` usages in the `paths` crate with
`OnceLock` from the standard library.

This allows us to drop the `lazy_static` dependency from this crate.

The paths are now exposed as accessor functions that reference a private
static value.

Release Notes:

- N/A

crates/fs/src/fs.rs

@@ -325,7 +325,7 @@ impl Fs for RealFs {
                 // Use the directory of the destination as temp dir to avoid
                 // invalid cross-device link error, and XDG_CACHE_DIR for fallback.
                 // See https://github.com/zed-industries/zed/pull/8437 for more details.
-                NamedTempFile::new_in(path.parent().unwrap_or(&paths::TEMP_DIR))
+                NamedTempFile::new_in(path.parent().unwrap_or(&paths::temp_dir()))
             } else {
                 NamedTempFile::new()
             }?;