ui2: Unsuppress and fix warnings (#3423)

This PR unsupresses the warnings in `ui2` and summarily fixes them.

Release Notes:

- N/A

crates/ui2/src/components/keybinding.rs

@@ -13,7 +13,7 @@ pub struct KeyBinding {
 impl RenderOnce for KeyBinding {
     type Rendered = Div;
 
-    fn render(self, cx: &mut WindowContext) -> Self::Rendered {
+    fn render(self, _cx: &mut WindowContext) -> Self::Rendered {
         div()
             .flex()
             .gap_2()