Make DSA storage multisample tests signal unsupported cases

Make DSA storage multisample tests signal unsupported cases

The current implementation has a single test instance that
loops over a collection of types and sizes and produces a
single pass/fail result. This means that the test fails
if any of the framebuffer configurations attempted
during the test is unsupported.

This patch rewrites the implementation so that we have a
separate test instance for each configuration instead.
This allows us to signal independent pass/fail/unsupported
results for each one.

Components: OpenGL
Issue: 503

Affects:
KHR-GL45.direct_state_access.textures_storage_multisample (removed)
KHR-GL45.direct_state_access.textures_storage_multisample_<imgtype>_<format> (added)
KHR-GL46.direct_state_access.textures_storage_multisample (removed)
KHR-GL46.direct_state_access.textures_storage_multisample_<imgtype>_<format> (added)

Change-Id: Ic0f1172d47f83b060a27a9c7537c1b85cb4a50e8