Lock screen preview in quick affordance picker.

ThemePicker parts.

- Hooks up the fragment to use the new lock screen preview binder
- Updates the UI such that the fragment layout is stable (the
  RecyclerViews for slots and affordance items don't change in height,
  allowing the preview view to have a stable size)

Note that this is adding the new lock screen preview to the quick
affordance screen only. This is where we'll do the majority of the
development for now and then move the reusable parts to the right screen
once the rest of the team works on that.

Bug: 261362750
Test: manual verification that the lock screen preview is showing up on
the quick affordance picker screen.

Change-Id: I6cd744053180fe706a344eb10e80f1231106f081