fix: Handle signals before crossterm events (#6170)

This is a workaround for a freeze when suspending Helix with C-z on
non-Windows systems. The check for the keyboard enhancement protocol
locks up crossterm's internal event reading/polling system by trying to
set up multiple concurrent readers. `input_stream.next()` sets up one
reader looking for regular crossterm events while the
`supports_keyboard_enhancement` query sets up another looking for
internal events. The latter hangs for two seconds or until the former
yields an event. By handling signals first we don't lock up the mutex
by trying to read keyboard events.

helix-term/src/application.rs

@@ -345,12 +345,12 @@ pub async fn event_loop_until_idle<S>(&mut self, input_stream: &mut S) -> bool
             tokio::select! {
                 biased;
 
-                Some(event) = input_stream.next() => {
-                    self.handle_terminal_events(event).await;
-                }
                 Some(signal) = self.signals.next() => {
                     self.handle_signals(signal).await;
                 }
+                Some(event) = input_stream.next() => {
+                    self.handle_terminal_events(event).await;
+                }
                 Some(callback) = self.jobs.futures.next() => {
                     self.jobs.handle_callback(&mut self.editor, &mut self.compositor, callback);
                     self.render().await;