Add example and functors related to matching particles by VELO LHCbIDs

• Adds the ISBASICPARTICLE functor.
• Adds test for FlattenDecayTree and particle matching

Needs Rec!3385 (merged)

DaVinciExamples/tests/qmtest/tupling.qms/test_davinci_tupling_from_hlt2_with_matching.qmt

@@ -16,7 +16,8 @@
   <argument name="program"><text>lbexec</text></argument>
   <argument name="args"><set>
     <text>DaVinciExamples.tupling.option_davinci_tupling_from_hlt2_with_matching:main</text>
-  </set></argument>
+  </set>
+  </argument>
   <argument name="options_yaml_fn"><text>$DAVINCIEXAMPLESROOT/example_data/Run255620.yaml</text></argument>
   <argument name="reference"><text>../refs/test_davinci_tupling_from_hlt2_with_matching.ref</text></argument>
   <argument name="error_reference"><text>../refs/empty.ref</text></argument>
@@ -25,5 +26,12 @@ from DaVinciTests.QMTest.DaVinciExclusions import preprocessor, counter_preproce
 from PyConf.components import findRootObjByDir
 validateWithReference(preproc = preprocessor, counter_preproc = counter_preprocessor)
 countErrorLines({"FATAL":0, "ERROR":0})
+
+# Check there are no NaN values in the ntuple except where expected.
+from DaVinciTests.QMTest.check_helpers import list_fields_with_nan
+
+l_test = list_fields_with_nan("Raw_DV_Ks_example.root", "DecayTreeTuple/DecayTree")
+if len(l_test) > 0:
+    causes.append("Unexpected list of branches with NaN values")
   </text></argument>
 </extension>