Revert "macOS: Improve deadkeys (#20515)" (#20570)

This reverts commit https://github.com/zed-industries/zed/pull/20515

I'm reverting for now to fix issues with key bindings on Nightly:
* `ctrl-c` and `ctrl-m` are being treated as `ctrl-enter`
* `ctrl-[` isn't working in vim mode
* there's a delay before `cmd-shift-[` switches tabs w/ vim mode enabled

Release Notes:

- N/A

crates/gpui/examples/input.rs

@@ -580,7 +580,7 @@ impl Render for InputExample {
             .children(self.recent_keystrokes.iter().rev().map(|ks| {
                 format!(
                     "{:} {}",
-                    ks.unparse(),
+                    ks,
                     if let Some(ime_key) = ks.ime_key.as_ref() {
                         format!("-> {}", ime_key)
                     } else {