Enable clippy::extra_unused_lifetimes (#8754)

This PR enables the
[`clippy::extra_unused_lifetimes`](https://rust-lang.github.io/rust-clippy/master/index.html#/extra_unused_lifetimes)
rule and fixes the outstanding violations.

Release Notes:

- N/A

crates/collab_ui/src/collab_panel.rs

@@ -1629,7 +1629,7 @@ impl CollabPanel {
         self.toggle_channel_collapsed(id, cx)
     }
 
-    fn toggle_channel_collapsed<'a>(&mut self, channel_id: ChannelId, cx: &mut ViewContext<Self>) {
+    fn toggle_channel_collapsed(&mut self, channel_id: ChannelId, cx: &mut ViewContext<Self>) {
         match self.collapsed_channels.binary_search(&channel_id) {
             Ok(ix) => {
                 self.collapsed_channels.remove(ix);