Adding the PDSmear systematics to SUSYTools to be used with a single initialisation

This MR is a replacement for !33364 (closed) in which there were discussions concerning the method used to duplicate the JER systematics. Due to the significant changes between the implementation in the previously mentioned MR, and this one (this one is much much simpler), it was easier to abandon the old MR and move everything here.

In order to run, the path to the FullJER systematic set needs to be set in the SUSYTools config file and the PDSmear needs to be set to true (currently false).

For the analyser, there are no changes to how the systematics are called from ST and they are not required to change their analysis frameworks in any way.All_JET_JER_UncertaintyComparisons.pdf

tagging @salderwe and @mrimoldi (whom provided the tests attached to this MR.)

Marco has again tested this and has shown that the PDSmear uncertainties are being applied independently from the nominal tool (and that the two uncertainties are being applied correctly, which can be seen in the attached PDF, where the PDSmear JER systematics, the non-PDSmear JER systematics and the nominal (no systematics) are all different.)

Cheers

John