Trig Nav Conversion Added FS nodes creation, enable chains filtering

This MR adds two functionalities:

1. creation of FS nodes (i.e. the nodes indicating the chain terminal node)
2. enables the filtering of the chains to be actually covered in the conversion

Tagging @wprzygod and @tamartin

Trigger/TrigEvent/TrigNavTools/share/testTrigR2ToR3NavGraphConversionV2.py

@@ -54,7 +54,8 @@ if __name__=='__main__':
     alg.doSelfValidation = False
     alg.Collections = ["xAOD::TrigElectronContainer"]
     alg.doCompression = True
-
+    # alg.Chains = ["HLT_e26_lhtight_idperf", "HLT_e26_lhmedium_nod0_ivarloose"]
+    alg.Chains = ["HLT_mu4_j80_xe80_pufit_2dphi10_L1MU4_J50_XE50_DPHI-J20s2XE30"]
     cfg.addEventAlgo(alg, sequenceName="AthAlgSeq")
     from OutputStreamAthenaPool.OutputStreamConfig import OutputStreamCfg
     outputType="AOD"