Users need to be able to specify whether or not PISA gets applied to pdb file

[TJGorrie]

Example use-case:

Mpro = monomer in pdb file but is a dimer in functionality.
mpro.pdb file should get gemmi/PISA'd into a dimeric structure by the pipeline prior to fragalysis-API

PlPro = monomer in pdb file, monomeric in functionality.
plpro.pdb file should not get gemmi/PISA'd into a dimeric structure by the pipeline prior to fragalysis-API

Solutions:

Table in XCDB to control how the pipeline behaves? If Monomeric do not run PISA/Gemmi step else use pisa/gemmi