Master: powheg log issues and ttj mi nnlops first implementation
requested to merge atlas-physics/pmg/mcexperts/powheg-experts/athena:master-Powheg-LogIssues-and-ttj_MiNNLOPS-FirstImplementation into master
This MR is a cherry-pick of !45670 (merged) in which the changes were applied to 21.6. See the description of that MR and AGENE-2016, AGENE-2024, and AGENE-2055 for more details.