set inset based padding to RNTester (#46354)

Summary:
Pull Request resolved: #46354

**Issue:**
With forced edge-to-edge on Android 15, RNTester title at top overlaps with the status bar and bottom tab bar overlaps with bottom nav bar

**Solution:**
Add margins based on inset values to the ReactRootView which is the contentView for RNTesterActivity which acts as global padding within RNTester

Changelog:
[Android][Changed] - Adding padding for RNTester on Android 15 forced edge-to-edge

Reviewed By: mdvacca

Differential Revision: D62247910

fbshipit-source-id: 7b35d0c2016b6897b5de436a4245c9e910559541

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

@@ -8,6 +8,12 @@
 package com.facebook.react.uiapp
 
 import android.os.Bundle
+import android.graphics.Color
+import android.graphics.drawable.ColorDrawable
+import android.view.View
+import android.widget.FrameLayout
+import androidx.core.view.ViewCompat
+import androidx.core.view.WindowInsetsCompat
 import com.facebook.react.FBRNTesterEndToEndHelper
 import com.facebook.react.ReactActivity
 import com.facebook.react.defaults.DefaultNewArchitectureEntryPoint.fabricEnabled
@@ -37,6 +43,28 @@ class RNTesterActivity : ReactActivity() {
         if (this::initialProps.isInitialized) initialProps else Bundle()
   }
 
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    // set background color so it will show below transparent system bars on forced edge-to-edge
+    this.window?.setBackgroundDrawable(ColorDrawable(Color.BLACK))
+    // register insets listener to update margins on the ReactRootView to avoid overlap w/ system bars
+    getReactDelegate()?.getReactRootView()?.let { rootView ->
+      val insetsType: Int =
+          WindowInsetsCompat.Type.systemBars() or WindowInsetsCompat.Type.displayCutout()
+
+      val windowInsetsListener = { view: View, windowInsets: WindowInsetsCompat ->
+        val insets = windowInsets.getInsets(insetsType)
+
+        (view.layoutParams as FrameLayout.LayoutParams).apply {
+          setMargins(insets.left, insets.top, insets.right, insets.bottom)
+        }
+
+        WindowInsetsCompat.CONSUMED
+      }
+      ViewCompat.setOnApplyWindowInsetsListener(rootView, windowInsetsListener)
+    }
+  }
+
   override fun createReactActivityDelegate() = RNTesterActivityDelegate(this, mainComponentName)
 
   override fun getMainComponentName() = "RNTesterApp"