macOS: Add key equivalents for non-Latin layouts (#20401)

Closes  #16343
Closes #10972

Release Notes:

- (breaking change) On macOS when using a keyboard that supports an
extended Latin character set (e.g. French, German, ...) keyboard
shortcuts are automatically updated so that they can be typed without
`option`. This fixes several long-standing problems where some keyboards
could not type some shortcuts.
- This mapping works the same way as
[macOS](https://developer.apple.com/documentation/swiftui/view/keyboardshortcut(_:modifiers:localization:)).
For example on a German keyboard shortcuts like `cmd->` become `cmd-:`,
`cmd-[` and `cmd-]` become `cmd-ö` and `cmd-ä`. This mapping happens at
the time keyboard layout files are read so the keybindings are visible
in the command palette. To opt out of this behavior for your custom
keyboard shortcuts, set `"use_layout_keys": true` in your binding
section. For the mappings used for each layout [see
here](https://github.com/zed-industries/zed/blob/a890df1863ca939ee7f0ada6e629b6f83eb18bc5/crates/settings/src/key_equivalents.rs#L7).

---------

Co-authored-by: Will <will@zed.dev>

crates/zed/src/zed.rs

@@ -808,6 +808,7 @@ pub fn handle_keymap_file_changes(
     VimModeSetting::register(cx);
 
     let (base_keymap_tx, mut base_keymap_rx) = mpsc::unbounded();
+    let (keyboard_layout_tx, mut keyboard_layout_rx) = mpsc::unbounded();
     let mut old_base_keymap = *BaseKeymap::get_global(cx);
     let mut old_vim_enabled = VimModeSetting::get_global(cx).0;
     cx.observe_global::<SettingsStore>(move |cx| {
@@ -822,6 +823,11 @@ pub fn handle_keymap_file_changes(
     })
     .detach();
 
+    cx.on_keyboard_layout_change(move |_| {
+        keyboard_layout_tx.unbounded_send(()).ok();
+    })
+    .detach();
+
     load_default_keymap(cx);
 
     cx.spawn(move |cx| async move {
@@ -829,6 +835,7 @@ pub fn handle_keymap_file_changes(
         loop {
             select_biased! {
                 _ = base_keymap_rx.next() => {}
+                _ = keyboard_layout_rx.next() => {}
                 user_keymap_content = user_keymap_file_rx.next() => {
                     if let Some(user_keymap_content) = user_keymap_content {
                         match KeymapFile::parse(&user_keymap_content) {
@@ -854,7 +861,7 @@ fn reload_keymaps(cx: &mut AppContext, keymap_content: &KeymapFile) {
     load_default_keymap(cx);
     keymap_content.clone().add_to_cx(cx).log_err();
     cx.set_menus(app_menus());
-    cx.set_dock_menu(vec![MenuItem::action("New Window", workspace::NewWindow)])
+    cx.set_dock_menu(vec![MenuItem::action("New Window", workspace::NewWindow)]);
 }
 
 pub fn load_default_keymap(cx: &mut AppContext) {