Reflect pipeline outputs as well as inputs, optionally from other stages

* We add an option to reflect inputs from other stages than vertex, if only a
  later subset of the stages is linked into the program.

Test/baseResults/reflection.options.frag.out

@@ -0,0 +1,10 @@
+reflection.frag
+Uniform reflection:
+
+Uniform block reflection:
+
+Pipeline input reflection:
+inval: offset 0, type 1406, size 0, index 0, binding -1, stages 0
+
+Pipeline output reflection:
+