migrate RNTesterActivity to Kotlin (facebook#39584)

Summary:
PR converts RNTesterActivity to Kotlin as requested in facebook#38825 .

## Changelog:

[INTERNAL] [CHANGED] - Migrate RNTesterActivity to Kotlin

Pull Request resolved: facebook#39584

Test Plan:
1. run `yarn android`
2. Check whether RN Tester runs as expected

Reviewed By: cortinico

Differential Revision: D49506304

Pulled By: ryancat

fbshipit-source-id: 7675b43e6ef1d09f9a6e09e5a70526fc59f07bbf

packages/rn-tester/android/app/src/main/java/com/facebook/react/uiapp/RNTesterActivity.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.uiapp
+
+import android.os.Bundle
+import com.facebook.react.ReactActivity
+import com.facebook.react.defaults.DefaultNewArchitectureEntryPoint.fabricEnabled
+import com.facebook.react.defaults.DefaultReactActivityDelegate
+
+class RNTesterActivity : ReactActivity() {
+  class RNTesterActivityDelegate(val activity: ReactActivity, mainComponentName: String) :
+      DefaultReactActivityDelegate(activity, mainComponentName, fabricEnabled) {
+    private val PARAM_ROUTE = "route"
+    private lateinit var initialProps: Bundle
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+      // Get remote param before calling super which uses it
+      val bundle = activity.getIntent()?.getExtras()
+
+      if (bundle != null && bundle.containsKey(PARAM_ROUTE)) {
+        val routeUri = "rntester://example/${bundle.getString(PARAM_ROUTE)}Example"
+        initialProps = Bundle()
+        initialProps?.putString("exampleFromAppetizeParams", routeUri)
+      }
+
+      super.onCreate(savedInstanceState)
+    }
+
+    override fun getLaunchOptions() = initialProps
+  }
+
+  override fun createReactActivityDelegate() = RNTesterActivityDelegate(this, mainComponentName)
+
+  override fun getMainComponentName() = "RNTesterApp"
+}