Eth65: Rename and stop exporting protocolVersion

This constant shouldn't be used outside `protocol_eth65`.

When we support multiple `eth/NN` versions side by side, or even just have
multiple code files, there's a risk some code would import just one of the
files (e.g. `protocol_eth65`), use `protocolVersion`, and incorrectly act as
though that version is the one active on the node.

In fact that happened, and now it can't happen.  Other code needs to query the
`EtheruemNode` to find what versions are really active.

Signed-off-by: Jamie Lokier <[email protected]>

nimbus/sync/protocol_eth65.nim

@@ -37,11 +37,11 @@ const
  maxBodiesFetch* = 128
  maxReceiptsFetch* = 256
  maxHeadersFetch* = 192
- protocolVersion* = 65
+ ethVersion = 65
 
 func toHex(x: KeccakHash): string = x.data.toHex
 
-p2pProtocol eth(version = protocolVersion,
+p2pProtocol eth(version = ethVersion,
  peerState = PeerState,
  useRequestIds = false):
 
@@ -56,7 +56,7 @@ p2pProtocol eth(version = protocolVersion,
  forkNext: chainForkId.nextFork.u256,
  )
 
- let m = await peer.status(protocolVersion,
+ let m = await peer.status(ethVersion,
  network.networkId,
  bestBlock.difficulty,
  bestBlock.blockHash,
@@ -82,7 +82,7 @@ p2pProtocol eth(version = protocolVersion,
  handshake:
  # User message 0x00: Status.
  proc status(peer: Peer,
- protocolVersion: uint,
+ ethVersionArg: uint,
  networkId: NetworkId,
  totalDifficulty: DifficultyInt,
  bestHash: KeccakHash,