This message notifies the peer that this node support Compact Block Relay.
Node should only send this message after protocol version >= 70014.
This message can indicate the High Bandwidth Relaying mode or Low Bandwidth Relaying mode by setting the `Mode` field.
Upon recepit of this message from the peer, node should announce new block via `cmpctblock` message if `Mode = 1`, or node should announce new block via `inv` or `header` message as defined in BIP-0130.