Introduce SpaScreenshotTests for SPA screenshot testing.

This CL introduces the SpaScreenshotTests to test a given View for multiple configurations (devices, theme and
orientation).

PreferenceScreenshotTest is added as an example, more screendiff tests will be added in follow-up CLs.

Test: presubmit
Bug: 256770697
Change-Id: I6b62d3cc248cab5bfe9f447e595ba393e9e3c848