Centralize always_allow logic when authorizing agent2 tools (#35988)

Release Notes:

- N/A

---------

Co-authored-by: Cole Miller <cole@zed.dev>
Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>
Co-authored-by: Agus Zubiaga <agus@zed.dev>
Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>

crates/fs/src/fs.rs

@@ -2172,6 +2172,9 @@ impl Fs for FakeFs {
     async fn atomic_write(&self, path: PathBuf, data: String) -> Result<()> {
         self.simulate_random_delay().await;
         let path = normalize_path(path.as_path());
+        if let Some(path) = path.parent() {
+            self.create_dir(path).await?;
+        }
         self.write_file_internal(path, data.into_bytes(), true)?;
         Ok(())
     }