Dismiss all modals when starting new activity

When starting new activity after previous activity showed modals
and did not dismiss them. The modal controller still had
registered modals even though we can't go back in the activity stack.

android/app/src/main/java/com/reactnativenavigation/modules/RctActivityModule.java

@@ -57,6 +57,9 @@ public class RctActivityModule extends ReactContextBaseJavaModule {
             if(ContextProvider.getActivityContext() instanceof RootActivity) {
                 context.overridePendingTransition(0, 0);
             }
+
+            // Dismiss modals associated with previous activity
+            ModalController.getInstance().dismissAllModals();
         }
     }
 
@@ -83,6 +86,9 @@ public class RctActivityModule extends ReactContextBaseJavaModule {
             if(ContextProvider.getActivityContext() instanceof RootActivity) {
                 context.overridePendingTransition(0, 0);
             }
+
+            // Dismiss modals associated with previous activity
+            ModalController.getInstance().dismissAllModals();
         }
     }