[New Common Data Format] JETS

Created by: comane

PR for the implementation of existing Jet datasets into new CommonData format.

The PR is branched from https://github.com/NNPDF/nnpdf/pull/1678. (See also previous PR here: https://github.com/NNPDF/nnpdf/pull/1699)

See table and report below for details

Dataset Old Name	Dataset New Name (including Observable Name)	Included In NNPDF40 Fit	General Notes	Status of Implementation	Extra Features (TODO)
ATLAS_1JET_8TEV_R06	ATLAS_1JET_8TEV_R06_PTY	❌	New implementation agrees with old one	The structure of the metadata.yaml file has been checked with the new reader.	Use d’Agostini prescription for the treatment of asymmetric uncertainties
ATLAS_1JET_8TEV_R06_DEC	Included in ATLAS_1JET_8TEV_R06	✅	New implementation does not agree with old one. Splitting of uncertainties as done in the .cc file is a bit weird. Better to use the HEPdata file directly?	The structure of the metadata.yaml file has been checked with the new reader.	Use d’Agostini prescription for the treatment of asymmetric uncertainties
ATLAS_2JET_7TEV_R06	ATLAS_2JET_7TEV_R06_M12Y	✅	New implementation does not agree with the old one. Bug in previous implementation (see also https://github.com/NNPDF/nnpdf/issues/1700 )	The structure of the metadata.yaml file has been checked with the new reader	Use d’Agostini prescription for the treatment of asymmetric uncertainties
CMS_1JET_8TEV		✅	There seems to be a bug in the old implementation, most likely introduced in the conversion correlation matrix to Covariance matrix	The structure of the metadata.yaml file has been checked with the new reader.	Use d’Agostini prescription for the treatment of asymmetric uncertainties
CMS_2JET_7TEV	CMS_2JET_7TEV_M12Y	✅	New Implementation agrees with old one.	The structure of the metadata.yaml file has been checked with the new reader.	Use d’Agostini prescription for the treatment of asymmetric uncertainties

Report of Comparison Legacy Datasets vs New Datasets: https://vp.nnpdf.science/5DpNBePRSne1TZ1Sfky6Kg==