Improve syntax of single initial condition file.

[jcblemai]

Branch init_file PR #54 add the ability to:

• load seeding from a single file (just added)

seeding:
  method: "FromFile"
  seeding_file: pathtoyourfile.csv  # ideally in a data/ subfolder

• load Initial Conditions from a single File (just added)

initial_conditions:
  method: "FromFile"
  initial_conditions_file: pathtoyourfile.csv/.parquet # ideally in a data/ subfolder

where this file is formatted like a seir file (nodes as columns, mc_name, …) and it’ll filter for the date that is the same as the config start_date (i.e the same as when we do a continuation resume)

But the existing method to load Initial Conditions from a single File is not really great
This method, which has a warning because there is no unit test covering it and I haven’t tested it in depth, but should work, sets initial condition from a csv file that is

initial_conditions:
  method: "SetInitialConditions"
  initial_conditions_file: pathtoyourfile.csv # ideally in a data/ subfolder

here the file is formatted as:

comp,place,amount
S_unvaccinated_ALPHA,01000,20

where the order of the meta compartment is the same as in the config (e.g you cannot say unvaccinated_S_ALPHA ). This method is not really finished because for now it requires that all compartments needs to be specified (I would like the user to be able to specify only a few, rest being 0 by default) and because a better syntax is needed (for meta compartments, more like seeding is)

[jlessler]

@alsnhll is going to review and see how best to handle open issues around this.