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/assistant2/src/active_thread.rs

@@ -1412,7 +1412,11 @@ impl ActiveThread {
         )
     }
 
-    fn render_tool_use(&self, tool_use: ToolUse, cx: &mut Context<Self>) -> impl IntoElement {
+    fn render_tool_use(
+        &self,
+        tool_use: ToolUse,
+        cx: &mut Context<Self>,
+    ) -> impl IntoElement + use<> {
         let is_open = self
             .expanded_tool_uses
             .get(&tool_use.id)

crates/assistant2/src/assistant_configuration.rs

@@ -105,7 +105,7 @@ impl AssistantConfiguration {
         &mut self,
         provider: &Arc<dyn LanguageModelProvider>,
         cx: &mut Context<Self>,
-    ) -> impl IntoElement {
+    ) -> impl IntoElement + use<> {
         let provider_id = provider.id().0.clone();
         let provider_name = provider.name().0.clone();
         let configuration_view = self

crates/assistant2/src/context_store.rs

@@ -687,7 +687,7 @@ pub fn refresh_context_store_text(
     context_store: Entity<ContextStore>,
     changed_buffers: &HashSet<Entity<Buffer>>,
     cx: &App,
-) -> impl Future<Output = Vec<ContextId>> {
+) -> impl Future<Output = Vec<ContextId>> + use<> {
     let mut tasks = Vec::new();
 
     for context in &context_store.read(cx).context {
@@ -855,7 +855,7 @@ fn refresh_thread_text(
 fn refresh_context_buffer(
     context_buffer: &ContextBuffer,
     cx: &App,
-) -> Option<impl Future<Output = ContextBuffer>> {
+) -> Option<impl Future<Output = ContextBuffer> + use<>> {
     let buffer = context_buffer.buffer.read(cx);
     let path = buffer_path_log_err(buffer)?;
     if buffer.version.changed_since(&context_buffer.version) {
@@ -875,7 +875,7 @@ fn refresh_context_buffer(
 fn refresh_context_symbol(
     context_symbol: &ContextSymbol,
     cx: &App,
-) -> Option<impl Future<Output = ContextSymbol>> {
+) -> Option<impl Future<Output = ContextSymbol> + use<>> {
     let buffer = context_symbol.buffer.read(cx);
     let path = buffer_path_log_err(buffer)?;
     let project_path = buffer.project_path(cx)?;

crates/assistant2/src/thread.rs

@@ -1192,7 +1192,7 @@ impl Thread {
     pub fn use_pending_tools(
         &mut self,
         cx: &mut Context<Self>,
-    ) -> impl IntoIterator<Item = PendingToolUse> {
+    ) -> impl IntoIterator<Item = PendingToolUse> + use<> {
         let request = self.to_completion_request(RequestKind::Chat, cx);
         let messages = Arc::new(request.messages);
         let pending_tool_uses = self