chore(rpc-types-mev): improve bundle API flexibility

[cakevm]

Changes for EthSendBundle, EthBundleHash and removal of SendBundleResponse:

• bundle_hash in EthBundleHash is optional. Not all builders return such a bundle hash
• Remove duplicate struct SendBundleResponse in favor of EthBundleHash
• New extra_fields as known from ChainConfig allow the user to add builder specific fields

Again a breaking change, but I have the feeling that it is worth it, for a better usability.

Update: Initially I replaced Vec with HashSet for fields like reverting_tx_hashes, but this would potentially lead to a non-deterministic bundle hash calculation. I reverted this change.

[cakevm]

I’m not sure, but Clippy used to complain whenever I added #[deprecated] to the struct. I believe the type mapping will achieve the same goal :)