Switch to EIP-1559 transactions

[ulope]

Abstract

Once full web3.py support for 1559 txs has landed we should start using it.
This will (hopefully) make our gas price calculations more predictable and also lower user gas costs.

Also see #7095
Blocked by: ethereum/web3.py#2066

Specification

TBD

Backwards Compatibility

N/A

[karlb]

The blocking issue is done. How would we set the new fee components? Can we do that reasonably without some kind of fee oracle?

[karlb]

We should remove the gas_price_strategy, since the web3py docs say

Gas price strategy is only supported for legacy transactions. The London fork introduced maxFeePerGas and maxPriorityFeePerGas transaction parameters which should be used over gasPrice whenever possible.

There is no progress on the fee oracle issue, so we'll have to decide on how to set maxFeePerGas and maxPriorityFeePerGas ourselves (or just leave them at the defaults). Any suggestions?