chore: Prepare for Rust edition bump to 2024 (without autofix) (#27791)

Successor to #27779 - in this PR I've applied changes manually, without
futzing with if let lifetimes at all.

Release Notes:

- N/A

crates/search/src/buffer_search.rs

@@ -936,12 +936,12 @@ impl BufferSearchBar {
         self.update_matches(!updated, window, cx)
     }
 
-    fn render_search_option_button(
+    fn render_search_option_button<Action: Fn(&ClickEvent, &mut Window, &mut App) + 'static>(
         &self,
         option: SearchOptions,
         focus_handle: FocusHandle,
-        action: impl Fn(&ClickEvent, &mut Window, &mut App) + 'static,
-    ) -> impl IntoElement {
+        action: Action,
+    ) -> impl IntoElement + use<Action> {
         let is_active = self.search_options.contains(option);
         option.as_button(is_active, focus_handle, action)
     }

crates/search/src/search.rs

@@ -105,12 +105,12 @@ impl SearchOptions {
         options
     }
 
-    pub fn as_button(
+    pub fn as_button<Action: Fn(&gpui::ClickEvent, &mut Window, &mut App) + 'static>(
         &self,
         active: bool,
         focus_handle: FocusHandle,
-        action: impl Fn(&gpui::ClickEvent, &mut Window, &mut App) + 'static,
-    ) -> impl IntoElement {
+        action: Action,
+    ) -> impl IntoElement + use<Action> {
         IconButton::new(self.label(), self.icon())
             .on_click(action)
             .style(ButtonStyle::Subtle)