android: try to add a Android TV Leanback launcher icon

Maybe it works on Android TV, but this doesn't work on a Fire Stick.

Updates tailscale/tailscale#4179

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

android/src/main/AndroidManifest.xml

@@ -15,7 +15,8 @@
 	<uses-feature android:name="android.hardware.touchscreen" android:required="false" />
 
 	<application android:label="Tailscale" android:icon="@mipmap/ic_launcher" android:roundIcon="@mipmap/ic_launcher_round"
-		android:name=".App" android:allowBackup="false">
+                     android:banner="@drawable/tv_banner"
+                     android:name=".App" android:allowBackup="false">
 		<activity android:name="IPNActivity"
 			android:label="@string/app_name"
 			android:theme="@style/Theme.GioApp"