In preparation of supporting vulkan. Draw/GPU tests should use
GPU_TEST or DRAW_TEST macros. These macros will run the test
on available drawing context backends like OpenGL or Vulkan.
As in master there is only an OpenGL backend nothing changed.
The draw manager test case initialized ghost, gpu and draw manager. This
change splits the base test case to GPU specific and draw manager
specific test case.
The GPU test base test case will be used for low level GPU tests.
