feat: Add more configurable paths for input data.

[ainar]

To make the code more usable as it is and to progress in line with the generalization of the pipeline (https://github.com/eqasim-org/ile-de-france/issues/139), I suggest adding the parameters below. It should also simplify the update of the input files.

• income_com_path (default: filosofi_2015/FILO_DISP_COM.xls),
• income_reg_path (default : filosofi_2015/FILO_DISP_REG.xls),
• income_year because the income year is needed to parse the column names in FiLoSoFi data (default: 15),
• od_pro_path (default: rp_2015/FD_MOBPRO_2015.dbf),
• od_sco_path (default: rp_2015/FD_MOBSCO_2015.dbf),
• codes_path (default: codes_2017/reference_IRIS_geo2017.xls),
• iris_path (default: codes_2017/reference_IRIS_geo2017.xls),
• population_path (default: rp_2015/base-ic-evol-struct-pop-2015.xls).

The name of the parameters and the default values are personal suggestions. We can discuss them if you want.

[sebhoerl]

For me it is good to merge. One remark: Theoretically, synpp understands hierarchical options now, so for instance, you should be able to requests soemthing like filosofi.municipalities_path and filosofi.regions_path and have it in the config file as

config:
  filosofi:
    municipalities_path: ...
    regions_path: ...

Could be good to structure the whole configuration better in the the future, but for now its fine, not sure this is even used somewhere yet and would need to be tested ;)