fix(android): ensure open and close run on main thread

Author: patrickkabwe

android/src/main/java/com/nitroinappbrowser/HybridNitroInAppBrowser.kt

@@ -4,17 +4,22 @@ import com.margelo.nitro.NitroModules
 import com.margelo.nitro.core.Promise
 import com.margelo.nitro.nitroinappbrowser.HybridNitroInAppBrowserSpec
 import com.margelo.nitro.nitroinappbrowser.NitroInAppBrowserOptions
+import kotlinx.coroutines.MainScope
+import kotlinx.coroutines.launch
 
 class HybridNitroInAppBrowser: HybridNitroInAppBrowserSpec() {
     private val inAppBrowser = NitroInAppBrowserImpl(NitroModules.applicationContext)
+    private val scope = MainScope()
 
     override fun open(url: String, options: NitroInAppBrowserOptions?): Promise<Unit> {
-        return Promise.async {
+        return Promise.async(scope) {
             inAppBrowser.open(url, options)
         }
     }
 
     override fun close() {
-        inAppBrowser.close()
+        scope.launch {
+            inAppBrowser.close()
+        }
     }
 }