Use alloy instead of ethers_core for decoding execution layer types

[ethDreamer]

Description

We currently use ethers_core in a few places to decode execution layer types. This crate is no longer maintained. But the reth team is maintaining another collection of crates under the name alloy to facilitate this functionality. We already use this for verifying the versioned hashes during optimistic sync. We should update the other locations as well.

[dospore]

Id be interested in putting a PR in for this issue

[michaelsproul]

@dospore Awesome, thanks! You should probably base your work off #4832 (or wait until it merges to unstable)

[dospore]

@michaelsproul making progress on this. Have a PR more or less ready to go working off #4832. Just needed some help with whats the best path with serialising. Since ethers_core::types::Transaction is serialisable but the alloy type (TxEnvelope) which is used in the linked pr is not. I can write a wrapper struct that converts from TxEnvelope into a serialisable type but thought id ask for some clarification first. Since there is also this Transaction type which matches the current ethers_core Transaction but it is not RlpDecodable which it will need to decode the raw tx here