Upgrade to PineAPPL v1

[Radonirinaunimi]

This PR tests the new Python interface of the upcoming PineAPPL v1. There are a few notable changes affecting pineko directly:

• The types of convolutions (be it for grids or FK tables) are accessed through the convolutions attributes. These information are no longer determined from the metadata (address the shortcomings discussed in Bump pineappl version nnpdf#2129 (comment) and Allow evolution and convolution with different ekos for a single grid  #181 (comment)).
• Grids can be evolved with an arbitrary number of EKOs (no longer limited to two operators). This removes the need for operator1 and operator2 in favor of just operators.
• Grids and FK tables can be convolved with an arbitrary number of PDFs (no longer limited to two PDFs). Similarly, this removes the need for pdf1 and pdf2 in favor of pdfs.
• Add a new variation of scale - which is the fragmentation scale xia.

The only remaining thing for which we will still require an ad-hoc hack/tweak is the checks that the PDFs are ordered according to the type of convolutions. This is an LHAPDF problem so there isn't much that we can do.

This will deprecate #192.

[cschwan]

When this is working I suggest you also try to implement #183 - this should decrease the time and space needed to perform an evolution. Also the required changes should be minimal.

[Radonirinaunimi]

When this is working I suggest you also try to implement #183 - this should decrease the time and space needed to perform an evolution. Also the required changes should be minimal.

Thanks for letting me know about this! I will surely do once this is working indeed.