[3/n] Add cache to PackageManager#getActivityInfo usage

Flag: com.android.window.flags.enable_modals_fullscreen_with_permission
Bug: 394714626
Test: atest WMShellUnitTests:DesktopModeCompatPolicyTest

Change-Id: I29ccc7acdc6ebdf045e1850be833059cc1f6430d
2 files changed