This PR starts with a few small commits of code cleanup. Reviewed
separately they should hopefully obviously be functionally no-ops. I'm
happy to strip these out and submit them separately if desired.
The final commit is to add support for older blocks as a parameter to
eth_getProof. In order to compute proofs, the function leverages the
staged sync unwinding code to bring the hashed state table back to its
historic state, as well as to build a list of trie nodes which need to
be invalidated/re-computed in the trie computation. Because these
operations could be expensive for very old blocks, it limits the
distance proofs are allowed from the head. It also adds some additional
checks for correctness, as well as tests which verify the
implementation.
This was discussed a bit on Discord in the db-format topic.
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Co-authored-by: Jason Yellick <jason@enya.ai>
