Apply darkmode style (#65182)

packages/flutter_tools/templates/app/android.tmpl/app/src/main/res/drawable/launch_background.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Modify this file to customize your launch splash screen -->
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:drawable="@android:color/white" />
+    <item android:drawable="?android:colorBackground" />
 
     <!-- You can insert your own image assets here -->
     <!-- <item>

packages/flutter_tools/templates/app/android.tmpl/app/src/main/res/values-night/styles.xml

+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is on -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <!-- Show a splash screen on the activity. Automatically removed when
+             Flutter draws its first frame -->
+        <item name="android:windowBackground">@drawable/launch_background</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+         
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Black.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>

packages/flutter_tools/templates/app/android.tmpl/app/src/main/res/values/styles.xml

 <?xml version="1.0" encoding="utf-8"?>
 <resources>
-    <!-- Theme applied to the Android Window while the process is starting -->
-    <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar">
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is off -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Light.NoTitleBar">
         <!-- Show a splash screen on the activity. Automatically removed when
              Flutter draws its first frame -->
         <item name="android:windowBackground">@drawable/launch_background</item>
@@ -12,7 +12,7 @@
          running.
          
          This Theme is only used starting with V2 of Flutter's Android embedding. -->
-    <style name="NormalTheme" parent="@android:style/Theme.Black.NoTitleBar">
-        <item name="android:windowBackground">@android:color/white</item>
+    <style name="NormalTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
     </style>
 </resources>

packages/flutter_tools/templates/template_manifest.json

@@ -27,6 +27,7 @@
         "templates/app/android.tmpl/app/src/main/res/mipmap-xxhdpi/ic_launcher.png",
         "templates/app/android.tmpl/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png",
         "templates/app/android.tmpl/app/src/main/res/values/styles.xml",
+        "templates/app/android.tmpl/app/src/main/res/values-night/styles.xml",
         "templates/app/android.tmpl/app/src/profile/AndroidManifest.xml.tmpl",
         "templates/app/android.tmpl/gradle/wrapper/gradle-wrapper.properties",
         "templates/app/android.tmpl/gradle.properties.tmpl",