feat: saveToken plugin for app groups on iOS

This will allow the share extension to access the Bearer token to send
images to the backend.

tauri-plugin-ios-shared-token/.gitignore

@@ -0,0 +1,17 @@
+/.vs
+.DS_Store
+.Thumbs.db
+*.sublime*
+.idea/
+debug.log
+package-lock.json
+.vscode/settings.json
+yarn.lock
+
+/.tauri
+/target
+Cargo.lock
+node_modules/
+
+dist-js
+dist