`eth_types` is being imported from many projects and ends up causing
long build times due to its extensive import lists - this PR starts
cleaning some of that up by moving the chain DB and RLP to their own
modules.
this PR also moves `keccakHash` to its own module and uses it in many
places.
Currently only setting `--styleCheck:hint` as there are some
dependency fixes required and the compiler seems to trip over the
findnode MessageKind, findnode Message field and the findNode
proc. Also over protocol.Protocol usage.