Update TaskFragmentToken for Activity relaunch

Before, we store the TaskFragmentToken in ActivityClientRecord from
LaunchActivityItem, which won't update if the Activity is relaunched.
Now, we update the token when the activity is reparented to make sure
the token is up-to-date when relaunched.

Also make sure that when activity is destroyed, it is no longer
available using SplitController#getContainerWithActivity(Activity).

Bug: 243330085
Test: atest WMJetpackUnitTests:TaskFragmentContainerTest
Change-Id: I37f1a442c6f1bfb40f04f61eb4f9a3d8d09733ee