Cleanups preparing for WindowContext refactor (#22475)

* Remove unnecessary WindowContext and ViewContext '_ lifetimes

* Removed some cases where WindowContext has a different name than `cx`.

Release Notes:

- N/A

crates/assistant/src/assistant_panel.rs

@@ -4966,8 +4966,8 @@ fn fold_toggle(
 ) -> impl Fn(
     MultiBufferRow,
     bool,
-    Arc<dyn Fn(bool, &mut WindowContext<'_>) + Send + Sync>,
-    &mut WindowContext<'_>,
+    Arc<dyn Fn(bool, &mut WindowContext) + Send + Sync>,
+    &mut WindowContext,
 ) -> AnyElement {
     move |row, is_folded, fold, _cx| {
         Disclosure::new((name, row.0 as u64), !is_folded)

crates/assistant/src/slash_command_picker.rs

@@ -27,8 +27,8 @@ enum SlashCommandEntry {
     Info(SlashCommandInfo),
     Advert {
         name: SharedString,
-        renderer: fn(&mut WindowContext<'_>) -> AnyElement,
-        on_confirm: fn(&mut WindowContext<'_>),
+        renderer: fn(&mut WindowContext) -> AnyElement,
+        on_confirm: fn(&mut WindowContext),
     },
 }