tests: Move HLSL tests to a subdirectory.

Approved-by: Giovanni Mascellani (@giomasce)
Approved-by: Francisco Casas (@fcasas)
Approved-by: Henri Verbeet (@hverbeet)
Approved-by: Alexandre Julliard (@julliard)
Merge-Request: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/248

tests/hlsl/math.shader_test

@@ -0,0 +1,15 @@
+[pixel shader]
+float4 main(uniform float4 a, uniform float2 b) : SV_TARGET
+{
+    float u = a.x, v = a.y, w = a.z, x = a.w, y = b.x, z = b.y;
+    return float4(x * y - z / w + --u / -v,
+            z * x / y + w / -v,
+            u + v - w,
+            x / y / w);
+}
+
+[test]
+uniform 0 float4 2.5 0.3 0.2 0.7
+uniform 4 float4 0.1 1.5 0.0 0.0
+draw quad
+probe all rgba (-12.43, 9.833333, 1.6, 35.0) 1