Add BcSmartspaceView to keyguard bottom area.

Screen capture: (with flag on)
  - cheetah: https://hsv.googleplex.com/5041267101663232
    - Note: ignore the Smartspace at the top.
      - This was taken with a slightly outdated cl.
  - felix: https://hsv.googleplex.com/6552804454825984
    - With the shade pulled down: https://hsv.googleplex.com/4612065063862272

Known limitations for this initial implemention:
  1. In this CL, ambient_indication_container is replaced by
smartspace_container, which contains the Smartspace. This is just for
exploration purpose. The end product should rank UMO and system messages
together with the Smartspace features, per product spec.
  2. Still need to update the logic to show/hide the smartspace when
     applicable. (E.g., when the shade is pulled down.)
  3. Pending UX spec for making it pretty. (at least not overlapping
     with other contents.)
  4. Haven't tested all combinations of devices and orientations.

Flag: ACONFIG com.android.systemui.smartspace_relocate_to_bottom DEVELOPMENT
Bug: 316212788
Test: Trigger Smartspace features (e.g. timer) and check lockscreen
Change-Id: Ib0581a95d44caaa9256a5a06d47b030a6e8f4052