fix(os): use an internal object instead of window.__TAURI__, closes #719 (#721)

fix(os): use an internal object instead of ` window.__TAURI__`, closes  #719

examples/api/src-tauri/src/main.rs

@@ -6,6 +6,5 @@
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
 
 fn main() {
-    #[cfg(desktop)]
-    api::run();
+    api_lib::run();
 }