Use SYSTEM_APPLICATION_OVERLAY instead of SYSTEM_ALERT_WINDOW for Taskbar

Test: Taskbar still shows up and works, can't hide it from Settings
Bug: 169054709
Change-Id: I0d2f9be8a0af2242472d8406bbc31a6aecaa9285
diff --git a/quickstep/AndroidManifest.xml b/quickstep/AndroidManifest.xml
index 9c14b85..7431551 100644
--- a/quickstep/AndroidManifest.xml
+++ b/quickstep/AndroidManifest.xml
@@ -41,7 +41,7 @@
     <uses-permission android:name="android.permission.MANAGE_ACCESSIBILITY"/>
 
     <uses-permission android:name="${packageName}.permission.HOTSEAT_EDU" />
-    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
+    <uses-permission android:name="android.permission.SYSTEM_APPLICATION_OVERLAY" />
 
     <application android:backupAgent="com.android.launcher3.LauncherBackupAgent"
          android:fullBackupOnly="true"