Allow collection of pricing from users

I have an EnBW charging price that ABRP knows about in principle (Mobility+ L), but it doesn't know the pricing I'd have (right now discounted at .31€/kWh), so it doesn't consider it as a priority during planning.

My idea here would be to let the user set/adjust the pricing for their contact (if the type is known) and to use that in planning. If enough users report the same pricing for a given contract, maybe update the database accordingly for all users.

Additionally it would be nice to be able to say “contract not listed” for a given provider and set the pricing for charging at that provider.

Cheers,

Sven