Add the additional JETUncertainties tool to run the PDSmear systematics with a single initialisation of SUSYTools.
In order to run, the path to the FullJER systematic set needs to be set in the SUSYTools config file. The PDSmear line needs to be uncommented (and set to true, again this has been left in the config file).
For the analyser, there are changes to how the systematics are called from ST (should be similar to how it is now done in the SUSYToolsTester file).
tagging @salderwe and @mrimoldi (for testing)
Marco has tested this and has shown that the PDSmear uncertainties are being applied separately from the nominal tool (and that the two uncertainties are being applied correctly).
(NB: this supersedes the previous MR which I closed: !31994 (closed) due to relatively significant changes that would have been needed in that branch to update to the latest SUSYTools/analysis base so making a new MR was quicker than fixing the old one.)