Migrate "isRotationAllowed" setting to LauncherPrefs.

This semi-complicated case requires use of a context in order to get the
default value. That is why it was migrated by itself.

Bug: 261635315
Test: Manually tested all the base functionality of the launcher.
Change-Id: I40d8ccd414402b55921a0a224264414d3245871b
4 files changed