Add multicomp wc

[danieleongari]

I'm adding a work chain built on @pzarabadip's MultiCompIsotherm wc.

It does, for a gas mixture:

• compute the blocking sphere and volpo for every component
• compute the kH via Widom for every component
• check if the material is selective enough (logic by @pzarabadip, to revise)
• run GCMC at adsorption: given P, T and composition
• run GCMC at desorption: given P, T and using composition inside the material at adsorption. This is a better approximation than assuming the comp@ads, but still an approximation because we should reiterate on the ratio of the working capacities.
• collect the main results in a Dict

The managing of the input parameters, especially for the molecules, need some rationalizations. The same for the output_parameters. I was considering building a work chain that is not limited to two GCMC calculation (ads, des), but can be extended to sample any number of conditions (here the name AdsorptionWC)... but constraining to only two (ads, des) is probably a clearer user case, allows for a simpler input/output/logic, especially when deciding to use the composition from the result of a prvious calculation.

[codecov-io]

Codecov Report

Merging #45 (0811b32) into develop (6c063cf) will decrease coverage by 4.07%. The diff coverage is 18.98%.

@@             Coverage Diff             @@
##           develop      #45      +/-   ##
===========================================
- Coverage    36.88%   32.81%   -4.08%     
===========================================
  Files           22       25       +3     
  Lines         1556     2008     +452     
===========================================
+ Hits           574      659      +85     
- Misses         982     1349     +367     

Impacted Files	Coverage Δ
aiida_lsmo/workchains/multicomp_ads_des.py	16.47% <16.47%> (ø)
aiida_lsmo/workchains/multicomp_gcmc.py	16.99% <16.99%> (ø)
aiida_lsmo/workchains/singlecomp_widom.py	22.50% <22.50%> (ø)
aiida_lsmo/workchains/__init__.py	100.00% <100.00%> (ø)
aiida_lsmo/workchains/isotherm.py	89.94% <100.00%> (ø)

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[danieleongari]

The PR is now ready for merging. The initial concept of one wc was split into 3 work chains:

• SinglecompWidom, to compute the Henry coefficient at different temperatures
• MulticompGcmc, to compute the uptake of a mixture at different T/P
• MulticompAdsDes, to compute the uptake of a mixture at a specific T/P for adsorption and desorption

The forcefields of some molecules were also added or fixed.