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/extension_host/src/extension_host.rs

@@ -398,7 +398,7 @@ impl ExtensionStore {
         &mut self,
         modified_extension: Option<Arc<str>>,
         cx: &mut Context<Self>,
-    ) -> impl Future<Output = ()> {
+    ) -> impl Future<Output = ()> + use<> {
         let (tx, rx) = oneshot::channel();
         self.reload_complete_senders.push(tx);
         self.reload_tx