2/2 Making bouncer shift on double tap when user chooser is visible

This change adds nice animation when bouncer/security swap sides with user chooser view.

The main changes are:
- extracting security animation code to SidedSecurityMode superclass and adding listener to security alpha during animation so that user chooser view can synchronize its alpha along with it.
- user switcher mode doesn't use gravity anymore to position views horizontally, now it uses X translation, just like one handed mode

Bouncer animation doesn't change at all compared to one handed mode and user chooser: fades out when bouncer fades out, shifts to the destination position and then fades in when bouncer fades in.

Bug: 220872694
Test: KeyguardSecurityContainerTest + open bouncer with user chooser on the side, double tap on the other side of the bouncer, see views swap positions with nice animation
Change-Id: I6ed2d2a6006063f63a8f9edf6da47abbfb7efb45