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/gpui/src/keymap/binding.rs

@@ -1,3 +1,5 @@
+use collections::HashMap;
+
 use crate::{Action, KeyBindingContextPredicate, Keystroke};
 use anyhow::Result;
 use smallvec::SmallVec;
@@ -22,22 +24,37 @@ impl Clone for KeyBinding {
 impl KeyBinding {
     /// Construct a new keybinding from the given data.
     pub fn new<A: Action>(keystrokes: &str, action: A, context_predicate: Option<&str>) -> Self {
-        Self::load(keystrokes, Box::new(action), context_predicate).unwrap()
+        Self::load(keystrokes, Box::new(action), context_predicate, None).unwrap()
     }
 
     /// Load a keybinding from the given raw data.
-    pub fn load(keystrokes: &str, action: Box<dyn Action>, context: Option<&str>) -> Result<Self> {
+    pub fn load(
+        keystrokes: &str,
+        action: Box<dyn Action>,
+        context: Option<&str>,
+        key_equivalents: Option<&HashMap<char, char>>,
+    ) -> Result<Self> {
         let context = if let Some(context) = context {
             Some(KeyBindingContextPredicate::parse(context)?)
         } else {
             None
         };
 
-        let keystrokes = keystrokes
+        let mut keystrokes: SmallVec<[Keystroke; 2]> = keystrokes
             .split_whitespace()
             .map(Keystroke::parse)
             .collect::<Result<_>>()?;
 
+        if let Some(equivalents) = key_equivalents {
+            for keystroke in keystrokes.iter_mut() {
+                if keystroke.key.chars().count() == 1 {
+                    if let Some(key) = equivalents.get(&keystroke.key.chars().next().unwrap()) {
+                        keystroke.key = key.to_string();
+                    }
+                }
+            }
+        }
+
         Ok(Self {
             keystrokes,
             action,