feat(notification): add plugin (#326)

plugins/notification/android/src/main/java/NotificationPlugin.kt

@@ -0,0 +1,31 @@
+package app.tauri.notification
+
+import android.app.Activity
+import app.tauri.annotation.Command
+import app.tauri.annotation.TauriPlugin
+import app.tauri.plugin.JSObject
+import app.tauri.plugin.Plugin
+import app.tauri.plugin.Invoke
+
+@TauriPlugin
+class NotificationPlugin(private val activity: Activity): Plugin(activity) {
+    @Command
+    fun requestPermission(invoke: Invoke) {
+        val ret = JSObject()
+        ret.put("permissionState", "granted")
+        invoke.resolve(ret)
+    }
+
+    @Command
+    fun permissionState(invoke: Invoke) {
+        val ret = JSObject()
+        ret.put("permissionState", "granted")
+        invoke.resolve(ret)
+    }
+
+    @Command
+    fun notify(invoke: Invoke) {
+        // TODO
+        invoke.resolve()
+    }
+}