Non-consuming conversion from BundleState to StateChangeset

[prestwich]

Currently the API is pub fn into_plain_state(self, is_value_known: OriginalValuesKnown) -> StateChangeset. This means that reth DB interfaces must consume the bundlestate in order to write plain state to DB.

Given that all information in the BundleState is efficiently memcopy-able, we could make pub fn to_plain_state(&self, is_value_known: OriginalValuesKnown) -> StateChangeset with relatively little overhead (deref-and-copy instead of copy-to-stack-and-copy). This version would copy AccountInfo and rely on bytes::Bytes internal efficient Clone for contracts.