gpui: Implement From<String> for ElementId (#44447)

Release Notes:

- N/A

## Before

```rs
div()
    .id(SharedString::from(format!("process-entry-{ix}-command")))
```

## After

```rs
div()
    .id(format!("process-entry-{ix}-command"))
```

crates/livekit_client/examples/test_app.rs

@@ -378,7 +378,7 @@ impl Render for LivekitWindow {
                             .when_some(state.audio_output_stream.as_ref(), |el, state| {
                                 el.child(
                                     button()
-                                        .id(SharedString::from(identity.0.clone()))
+                                        .id(identity.0.clone())
                                         .child(if state.0.is_enabled() {
                                             "Deafen"
                                         } else {