Extend property to enable remote animation for keyguard.

There are two types of keyguard invovlved app transitions. Instead of
enabling / disabling remote animation for all such transitions, we can
now enable remote animation one by one.

Disable remote animation for all keyguard transitions.
% adb shell setprop persist.wm.enable_remote_keyguard_animation 0

Enable remote animation only for keyguard going away transition
(default).
% adb shell setprop persist.wm.enable_remote_keyguard_animation 1

Enable remote animation for both keyguard going away and (un)occlude
transition.
% adb shell setprop persist.wm.enable_remote_keyguard_animation 2

After setting the property, you need to restart shell and sysui, or reboot
the device.

Test: No-op chaneg. Pass existing tests.
Bug: 166736690
Change-Id: I81cf31fe60583f0fe0d9f46c3189fc0309e8374f