Add option to reflect buffer blocks & variables separately to uniforms

* Also note the uniform indices of atomic counter buffers

Test/baseResults/reflection.options.frag.out

@@ -3,6 +3,10 @@ Uniform reflection:
 
 Uniform block reflection:
 
+Buffer variable reflection:
+
+Buffer block reflection:
+
 Pipeline input reflection:
 inval: offset 0, type 1406, size 0, index 0, binding -1, stages 0