android: attempt to fix assertion errors in ReactInstanceManager

This is the main one:
df4e67fe75/ReactAndroid/src/main/java/com/facebook/react/ReactInstanceManager.java (L512)

Why this happens is a mystery wrapped in an enigma.

android/sdk/src/main/java/org/jitsi/meet/sdk/BaseReactView.java

 
         setBackgroundColor(BACKGROUND_COLOR);
 
-        ReactInstanceManagerHolder.initReactInstanceManager(
-            ((Activity) context).getApplication());
+        ReactInstanceManagerHolder.initReactInstanceManager((Activity)context);
 
         // Hook this BaseReactView into ExternalAPI.
         externalAPIScope = UUID.randomUUID().toString();

android/sdk/src/main/java/org/jitsi/meet/sdk/JitsiMeetActivityDelegate.java

 import com.calendarevents.CalendarEventsPackage;
 import com.facebook.react.ReactInstanceManager;
 import com.facebook.react.bridge.Callback;
+import com.facebook.react.bridge.ReactContext;
 import com.facebook.react.modules.core.PermissionListener;
 
 /**
             = ReactInstanceManagerHolder.getReactInstanceManager();
 
         if (reactInstanceManager != null) {
-            reactInstanceManager.onHostPause(activity);
+            // Try to avoid a crash because some devices trip on this assert:
+            // https://github.com/facebook/react-native/blob/df4e67fe75d781d1eb264128cadf079989542755/ReactAndroid/src/main/java/com/facebook/react/ReactInstanceManager.java#L512
+            // Why this happens is a mystery wrapped in an enigma.
+            ReactContext reactContext = reactInstanceManager.getCurrentReactContext();
+            if (activity == reactContext.getCurrentActivity()) {
+                reactInstanceManager.onHostPause(activity);
+            }
         }
     }
 

android/sdk/src/main/java/org/jitsi/meet/sdk/ReactInstanceManagerHolder.java

 package org.jitsi.meet.sdk;
 
 import android.app.Activity;
-import android.app.Application;
 import android.support.annotation.Nullable;
 
 import com.facebook.react.ReactInstanceManager;
      * time. All {@code ReactRootView} instances will be tied to the one and
      * only {@code ReactInstanceManager}.
      *
-     * @param application {@code Application} instance which is running.
+     * @param activity {@code Activity} current running Activity.
      */
-    static void initReactInstanceManager(Application application) {
+    static void initReactInstanceManager(Activity activity) {
         if (reactInstanceManager != null) {
             return;
         }
 
         reactInstanceManager
             = ReactInstanceManager.builder()
-                .setApplication(application)
+                .setApplication(activity.getApplication())
+                .setCurrentActivity(activity)
                 .setBundleAssetName("index.android.bundle")
                 .setJSMainModulePath("index.android")
                 .addPackages(packages)