Resolve ATLTAU-1758 and starts ATLTAU-1755
Closes ATLTAU-1758 Migration of DiTauSmearingTool (R21.2->master) which is the last remaining tool in TauAnalysisTool in the R21.2->master migration. This MR also starts on ATLTAU-1755 which involves migration of unit tests from R21.2->master. This MR migrates the tests, and updates the makefile. Further testing will follow to fully close ATLTAU-1755.
Edited by Guillermo Nicolas Hamity