Separate ekos in the local folders

[scarlehoff]

While in the server the ekos and the fktables are now separated, because it was easier to ensure that people didn't have to redownload theories, we left the ekos inside the theory folder locally.

However, the result is that people uploads ekos inside the theory folder to the server, which can be a problem due to storage limitations (e.g., in the CI)

Therefore it will be necessary to separate ekos and theories also locally. It is a simple thing to do:

1. Add a new folder in the nnprofile for ekos.
2. Decouple, in the loader, the eko from the theory.
3. Test vp-get and evolven3fit
4. Bonus: decouple, in evolven3fit, the theory from the eko. It is not necessary to have the fktables to evolve a fit. This is tricky since loading a theory with the API will check whether the folder exists. It might need to be able to add a theory_meta routine that can read the database without downloading the corresponding theory.

To see a bit how things work, you can start by downloading some theories locally:

vp-get theoryID 41000000
vp-get eko 41000000

The first command will download the theory, the second the eko.tar inside the theory_41000000 directory.

vp-get eko 41000000

This command instead will first download (or check that it exists) theory_41000000 and only then download the eko.

Most of the logic that needs change is in loader.py

e.g.,

nnpdf/validphys2/src/validphys/loader.py

Line 529 in e01e21e

def check_eko(self, theoryID):