feat(single-instance): add MacOs unix domain socket impl (#1035)

* feat(single-instance): add macos implementation

* chore(single-instance): test MacOs by adding CLI to example

* feat(single-instance): simplify macOS implementation

* chore(single-instance): address remarks

plugins/single-instance/examples/vanilla/src-tauri/src/main.rs

@@ -9,6 +9,7 @@
 
 fn main() {
   tauri::Builder::default()
+    .plugin(tauri_plugin_cli::init())
     .plugin(tauri_plugin_single_instance::init(|app, argv, cwd| {
       println!("{}, {argv:?}, {cwd}", app.package_info().name);
     }))