Draft: vkd3d-shader/hlsl: Implement strings
Strings are opaque objects in HLSL. This implements recognizing string
literals and the string type.
This should fix the bug marked below but I'm not sure how to get my hands on a copy of Lego Star Wars Saga to test it properly.
This is a super-duper draft MR; I'm certain there's problems with it. I do at least have a passing test, though.