* Instead of only doing a very lightweight check to see if the API is available
up-front, we now share the API initialisation among all API tests far enough
to determine availability of extensions, features, etc. Then we can precisely
determine which tests are available and which aren't before running.
* This is primarily for the benefit of GL/VK where we need to feature-detect for
some extensions or functionality that requires selecting a device, e.g. D3D12
can be more easily detected with a quick check.
* We'll run this once and cache the results when running tests from python so we
can do a better job of filtering out tests that the current machine doesn't
support.
* Built entirely independently of the main renderdoc build (for now).
* Contains python scripts & framework for running tests on a renderdoc build,
which will be run nightly.
baldurk