[Feature request]: refactor gempyor model build / run to use ABC

[pearsonca]

Label

dependency, enhancement, gempyor

Priority Label

medium priority

Is your feature request related to a problem? Please describe.

Shift associated with #432 - do this somewhat in parallel with #432, but should at least draft that first to represent "preferred" interface / boundary.

Is your feature request related to a new application, scenario round, pathogen? Please describe.

No response

Describe the solution you'd like

Refactor current simulate function to distinguish:

• build step: should create and store a pickled object according to configuration specification.
• run step: should receive parameters (not configuration file) and emit timeseries object (not store it)
• separate out reading from / writing to do disk
• separate out any "looping" constructs