Unify Flexible and Expanded elements

We'll use the name Expanded for something else now.

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/theme_selector/src/theme_selector.rs

@@ -293,7 +293,7 @@ impl View for ThemeSelector {
                 Container::new(
                     Flex::new(Axis::Vertical)
                         .with_child(ChildView::new(self.query_editor.id()).boxed())
-                        .with_child(Flexible::new(1.0, self.render_matches(cx)).boxed())
+                        .with_child(Flexible::new(1.0, false, self.render_matches(cx)).boxed())
                         .boxed(),
                 )
                 .with_style(settings.theme.selector.container)