Resolve request permission call when permission already exists

Problem:
If permission is already enabled, the call to `OneSignal.getNotifications().requestPermission(fallbackToSettings, Continue.with(...)` never suspends and returns early and the Continue.with code block never runs. As a result, we would not be able to resolve the promise over the bridge.

Solution:
Before calling that method, do a permission check and return true early.

android/src/main/java/com/onesignal/rnonesignalandroid/RNOneSignal.java

@@ -427,6 +427,13 @@ public void onNotificationPermissionChange(boolean permission) {
 
     @ReactMethod
     public void requestNotificationPermission(final boolean fallbackToSettings, Promise promise) {
+        // if permission already exists, no suspend is called so the Continue.with never runs below
+        boolean enabled = OneSignal.getNotifications().getPermission();
+        if (enabled) {
+            promise.resolve(true);
+            return;
+        }
+
         OneSignal.getNotifications().requestPermission(fallbackToSettings, Continue.with(result -> {
             if (result.isSuccess()) {
                 promise.resolve(result.getData());