[2/n] Include default home package in windowing exemptions check

Test desktop and external display system shortcuts with default home
package.

Flag: NONE bug fix
Test: atest -c NexusLauncherTests:com.android.quickstep.DesktopSystemShortcutTest,
      atest -c NexusLauncherTests:com.android.quickstep.ExternalDisplaySystemShortcutTest
Fixes: 389906224
Change-Id: I0d48ac3ffe995ebefffd1ea1b6892a72a3d3a4f1