Add fake and test implementations for SpatialAnnotation.

This change introduces TestSpatialAnnotation and FakeRuntimeSpatialAnnotation to enable simulated spatial annotations in the test environment. These classes allow tests to programmatically configure and update spatial annotation properties, such as poses and tracking states, to verify UI and layout behavior. Unit tests for the fake implementation are also included.

RelNote: Added `TestSpatialAnnotation` to allow programmatic simulation of spatial annotations in automated tests.

Bug: 543096679
Bug: 548634007
Test: Associated unit tests.
Change-Id: If233588d358900ddbbccd1e5120c340f1355144c