gpui: Introduce PlatformKeyboardLayout trait for human-friendly keyboard layout names (#29049)

This PR adds a new `PlatformKeyboardLayout` trait with two methods:
`id(&self) -> &str` and `name(&self) -> &str`. The `id()` method returns
a unique identifier for the keyboard layout, while `name()` provides a
human-readable name. This distinction is especially important on
Windows, where the `id` and `name` can be quite different. For example,
the French layout has an `id` of `0000040C`, which is not
human-readable, whereas the `name` would simply be `French`. Currently,
the existing `keyboard_layout()` method returns what's essentially the
same as `id()` in this new design.

This PR implements the `name()` method for both Windows and macOS. On
Linux, for now, `name()` still returns the same value as `id()`.

Release Notes:

- N/A

Cargo.lock

@@ -6171,6 +6171,7 @@ dependencies = [
  "windows 0.61.1",
  "windows-core 0.61.0",
  "windows-numerics",
+ "windows-registry 0.5.1",
  "workspace-hack",
  "x11-clipboard",
  "x11rb",
@@ -11930,7 +11931,7 @@ dependencies = [
  "wasm-bindgen-futures",
  "wasm-streams",
  "web-sys",
- "windows-registry",
+ "windows-registry 0.2.0",
 ]
 
 [[package]]
@@ -17044,6 +17045,17 @@ dependencies = [
  "windows-targets 0.52.6",
 ]
 
+[[package]]
+name = "windows-registry"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ad1da3e436dc7653dfdf3da67332e22bff09bb0e28b0239e1624499c7830842e"
+dependencies = [
+ "windows-link",
+ "windows-result 0.3.2",
+ "windows-strings 0.4.0",
+]
+
 [[package]]
 name = "windows-result"
 version = "0.1.2"