Move the setActiveDevice logic from Settings to SettingsLib (1/2)

Currently the Settings app handles the logic of setting active device;
however, this should be handled by SettingsLib so the logic can be shared.

Bug: 75984255
Test: robolectric test
Change-Id: Ia44e16c550d5b57c985e29e46e17044a895b495a
Merged-In: Ia44e16c550d5b57c985e29e46e17044a895b495a
(cherry picked from commit 6a416327)