L0 projections from command line

[jacoterh]

This PR adds support for specifying the noise level (L0/L1) added to the projections directly from the command line.

Creating projections

Fits with projections follow a two-step process. First, one creates projected datasets (typically with reduced statistical
and systematic uncertainties) as .yaml files in the standard SMEFiT format with the following command,

smefit PROJ --lumi <luminosity> --noise <noise level> /path/to/projection_runcard.yaml

where <luminosity> specifies the luminosity of the projection in :math:{\rm fb}^{-1}. The noise level <luminosity>
can be either L0 are L1 corresponding to either level 0 or level 1 projections respectively. In level 0 projections,
the experimental central value coincides exactly with the theory prediction, while the experimental central values are fluctuated around the theory prediction according to the experimental uncertainties in case of level 1. If <noise level> is not specified, level 0 is assumed. If <luminosity> is not specified, the original luminosities are kept and the uncertainties are not rescaled. The projection_runcard specifies which datasets need to be extrapolated, by which factor to reduce the systematics, and sets the necessary paths:

[jacoterh]

@arossia94 this you could use for the updated projections in ZH

[LucaMantani]

Suggested change

	"--noise",
	type=str,
	default="L0",
	required=False,
	help="Noise level for the projection, choose between L0 or L1. Assumes L0 by default.",
	"--noise",
	type=click.Choice(["L0", "L1"], case_sensitive=True),
	default="L0",
	required=False,
	help="Noise level for the projection, choose between L0 or L1. Assumes L0 by default.",

This should enforce that only L1 and L0 are recognised otherwise gives error, would be good to test it.

[LucaMantani]

From the current implementation, I believe that if one gives --noise l1 with l lowercase, one would get L0 data.