Validation layer should have message for graphics requirement function not called

Apparently some runtimes haven't updated to the new error code for this situation and there's no warning currently. see https://github.com/KhronosGroup/OpenXR-SDK-Source/issues/288

We do have some state-related stuff in parts of our generation scripts, that we ended up not actually using yet. Would it make it easier to support in the validation layer if we marked those get requirements calls as transitioning to some state?

Start by reading the linked OpenXR-SDK-Source issue 288 and the generation scripts and validation-layer code mentioned here. Determine how an uncalled graphics requirements function should be detected for runtimes using the older error code; done means the validation layer provides a warning for that situation.

Written by the indexing model from the issue text.