Generate the fees table dynamically using JSON-RPC

[PaulRBerg]

Like #332 but for fees.

Will wait for the next releases (Lockup v3.0, Flow v2.0, and Airdrops v2.0) to be published before building this since we now have oracles integrated in the contracts and we can target fiat fees (as opposed to using hard-coded ETH amounts, i.e., how we did it historically).