Add range iterator to iterate over ethereum state (state + storage trees)

[tanishqjasoria]

For verkle transition, we need a iterator over the current ethereum state to move it to the new verkle tree. The idea is to iterate over the accounts in sequence of path [Keccak(Address)]. As soon as we encounter an account with storage tree, pause the account iterator and start moving leaves from the storage tree and then resume with the account iterator. Current plan is to treat the code as a single leaf.