Python: Unify normal dataflow test setup

I went with NormalDataflowTest to signify that if you don't know what
you're looking for, this is probably the one. I did not want to just
call it DataflowTest, since that becomes a big vague when there are also
`FlowTest.qll` and `MaximalFlowTest.qll` -- I'm open to renaming this
though 👍

python/ql/test/experimental/dataflow/TestUtil/NormalDataflowTest.qll

@@ -1,6 +1,7 @@
 import python
 import experimental.dataflow.TestUtil.FlowTest
 import experimental.dataflow.testConfig
+private import semmle.python.dataflow.new.internal.PrintNode
 
 class DataFlowTest extends FlowTest {
   DataFlowTest() { this = "DataFlowTest" }
@@ -10,4 +11,8 @@ class DataFlowTest extends FlowTest {
   override predicate relevantFlow(DataFlow::Node source, DataFlow::Node sink) {
     exists(TestConfiguration cfg | cfg.hasFlow(source, sink))
   }
+
+  override predicate hasActualResult(Location location, string element, string tag, string value) {
+    super.hasActualResult(location, element, tag, value)
+  }
 }

python/ql/test/experimental/dataflow/coverage/NormalDataflowTest.ql

@@ -0,0 +1,2 @@
+import python
+import experimental.dataflow.TestUtil.NormalDataflowTest

python/ql/test/experimental/dataflow/fieldflow/NormalDataflowTest.ql

@@ -0,0 +1,2 @@
+import python
+import experimental.dataflow.TestUtil.NormalDataflowTest

python/ql/test/experimental/dataflow/fieldflow/dataflowTest.ql

@@ -1,13 +0,0 @@
-import python
-import experimental.dataflow.TestUtil.FlowTest
-import experimental.dataflow.testConfig
-
-class DataFlowTest extends FlowTest {
-  DataFlowTest() { this = "DataFlowTest" }
-
-  override string flowTag() { result = "flow" }
-
-  override predicate relevantFlow(DataFlow::Node source, DataFlow::Node sink) {
-    exists(TestConfiguration cfg | cfg.hasFlow(source, sink))
-  }
-}

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

@@ -0,0 +1,2 @@
+import python
+import experimental.dataflow.TestUtil.NormalDataflowTest

python/ql/test/experimental/dataflow/match/dataflowTest.ql

@@ -1,13 +0,0 @@
-import python
-import experimental.dataflow.TestUtil.FlowTest
-import experimental.dataflow.testConfig
-
-class DataFlowTest extends FlowTest {
-  DataFlowTest() { this = "DataFlowTest" }
-
-  override string flowTag() { result = "flow" }
-
-  override predicate relevantFlow(DataFlow::Node source, DataFlow::Node sink) {
-    exists(TestConfiguration cfg | cfg.hasFlow(source, sink))
-  }
-}