dfc-fermata: add Katie's Solara and Louis's Backpack

[JGreenlee]

Got MPG values from fueleconomy.gov for the cars I could (Abby's Katie's, and mine). Then calculated kgCo2PerKm values using the mpg_to_co2_per_km function from e-mission-common

mpgs = {
    'car_katie_solara': 21,
    'car_jack_mazda3': 33,
    'car_abbys_prius': 48,
}

for car, mpg in mpgs.items():
    print(f"{car} has MPG {mpg} and CO2 per km {mpg_to_co2_per_km(mpg):.5f}")

car_katie_solara has MPG 21 and CO2 per km 0.26364
car_jack_mazda3 has MPG 33 and CO2 per km 0.16777
car_abbys_prius has MPG 48 and CO2 per km 0.11534

For the GSA vehicles, we don't know the model years yet, so it will have to wait

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Since Louis's backpack is a fake vehicle, I just gave it 100 MPGe (in the ballpark for plug-in hybrids)