Python: Require MISSING: flow annotations for normal data-flow tests

I had to rewrite the SINK1-SINK7 definitions, since this new requirement
complained that we had to add this `MISSING: flow` annotation :D

Doing this implementation also revealed that there was a bug, since I
did not compare files when checking for these `MISSING:` annotations. So
fixed that up in the implementation for inline taint tests as well.

(extra whitespace in argumentPassing.py to avoid changing line numbers
for other tests)

python/ql/test/experimental/dataflow/match/NormalDataflowTest.expected

@@ -0,0 +1,2 @@
+missingAnnotationOnSINK
+failures