This function uses expect_known_value
to save a representation of the scene. During the comparison, the scene
is modified so that non-reproducible aspects are standardized
or omitted:
object ids are changed to start at 1.
system-specific font names and texture names are deleted.
the window is shifted to the top left of the screen.
Calls to expect_known_scene() enable testthat::local_edition(2)
for the duration of the call, so it will work in testthat “3rd edition”.