Appconfig support for iOS and Android (#856)

* AppConfig support for iOS

* AppConfig support for Android

* Fix typo

* Java feedback review

android/app/src/main/java/com/mattermost/rnbeta/MattermostManagedModule.java

@@ -0,0 +1,65 @@
+package com.mattermost.rnbeta;
+
+import android.app.Application;
+import android.content.Context;
+import android.os.Bundle;
+
+import com.facebook.react.bridge.Arguments;
+import com.facebook.react.bridge.NativeModule;
+import com.facebook.react.bridge.ReactApplicationContext;
+import com.facebook.react.bridge.ReactContext;
+import com.facebook.react.bridge.ReactContextBaseJavaModule;
+import com.facebook.react.bridge.ReactMethod;
+import com.facebook.react.bridge.Promise;
+
+public class MattermostManagedModule extends ReactContextBaseJavaModule {
+    private static MattermostManagedModule instance;
+
+    private boolean shouldBlurAppScreen = false;
+
+    private MattermostManagedModule(ReactApplicationContext reactContext) {
+        super(reactContext);
+    }
+
+    public static MattermostManagedModule getInstance(ReactApplicationContext reactContext) {
+        if (instance == null) {
+            instance = new MattermostManagedModule(reactContext);
+        }
+
+        return instance;
+    }
+
+    public static MattermostManagedModule getInstance() {
+        return instance;
+    }
+
+    @Override
+    public String getName() {
+        return "MattermostManaged";
+    }
+
+    @ReactMethod
+    public void blurAppScreen(boolean enabled) {
+        shouldBlurAppScreen = enabled;
+    }
+
+    public boolean isBlurAppScreenEnabled() {
+        return shouldBlurAppScreen;
+    }
+
+    @ReactMethod
+    public void getConfig(final Promise promise) {
+        try {
+            Bundle config = NotificationsLifecycleFacade.getInstance().getManagedConfig();
+
+            if (config != null) {
+                Object result = Arguments.fromBundle(config);
+                promise.resolve(result);
+            } else {
+                throw new Exception("The MDM vendor has not sent any Managed configuration");
+            }
+        } catch (Exception e) {
+            promise.reject("no managed configuration", e);
+        }
+    }
+}