Show diagnostic codes (#29296)

Closes #28135
Closes #4388
Closes #28136

Release Notes:

- diagnostics: Show the diagnostic code if available

---------

Co-authored-by: Neo Nie <nihgwu@live.com>
Co-authored-by: Zed AI <ai+claude-3.7@zed.dev>

crates/diagnostics/src/diagnostics.rs

@@ -416,6 +416,7 @@ impl ProjectDiagnosticsEditor {
                         group,
                         buffer_snapshot.remote_id(),
                         Some(this.clone()),
+                        true,
                         cx,
                     )
                 })?;