vkd3d-shader/hlsl: Record default values for uniforms and constant buffers.

Approved-by: Elizabeth Figura (@zfigura)
Approved-by: Henri Verbeet (@hverbeet)
Merge-Request: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/787

tests/hlsl/strings.shader_test

@@ -8,7 +8,7 @@ float4 main() : sv_target
     return 0;
 }
 
-[pixel shader todo]
+[pixel shader]
 typedef float4 sTring;
 sTring var = float4(1, 2, 3, 4);