INSEE: unit multipliers are missing

Description

When we look at series from INSEE, we don't know the unit of the series.

For example: https://db.nomics.world/INSEE/CNA-2014-PIB/A.CNA_PIB.S0.VAL.PIB.NNTOTAL.VALEUR_ABSOLUE.FE.EUROS_COURANTS.BRUT.

We know GDP of France is approximately 2000 billions of euros but we have 2291705 (for 2017).

However, in the source, we have the information. Considering the previous example, see https://git.nomics.world/dbnomics-source-data/insee-source-data/blob/master/data/CNA-2014-PIB.xml. We have in the xml UNIT_MULT="6", which means figures in the dataset should be multiplied by 10e6. We must add this information.

Tasks

• update the convert.py script to add the unit multiplier to converted data