So it could be used by both the OpenGL and the Vulkan driver.
In addition to the move, some small changes were needed to be made on
the API. For example, the simulator was receiving v3d_screen on
initialization, and that code setted v3d_screen->sim_file. Now it
returns the new sim_file created.
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5666>
