Merge development branch "21.2-zdc-dev-Bill-standalone" into 21.2
- Updates to pulse fitting to improve performance for 2018 PbPb
- Add repass for the pulse fitting to reduce the effect of the low energy peak (lower than 1n peak) which is due to the large pile-up events.
- Improve the baseline matching performance for delayed and undelayed samples.
- Change the 2018 fit function to "FermiExpLinear".
- Update separate test tool files in "tools" folder.