Calculate CO2 equivalent values using global warming potentials about open-grid-emissions HOT 2 CLOSED

This EPA page has a good explainer of these topics: https://www.epa.gov/ghgemissions/understanding-global-warming-potentials

from open-grid-emissions.

In #131, we have implemented the following:

• Although we still do not calculate CO2e values in our pipeline (although we should add this soon), this updates the function for calculating those values once we choose to implement that
• Update the format of the ipcc_gwp table from wide to long
• Adds AR6 data
• Adds a column for the year that the AR was published, so that the correct AR to use can be automatically chosen based on the data year.

from open-grid-emissions.