aquatic_ws_protocol: WebTorrent tracker protocol

WebTorrent tracker message parsing and serialization.

lib.rs:

WebTorrent protocol implementation

Typical announce workflow:

• Peer A sends announce request with info hash and offers
• Tracker sends on offers to other peers announcing with that info hash and sends back announce response to peer A
• Tracker receives answers to those offers from other peers and send them on to peer A

Typical scrape workflow

• Peer sends scrape request and receives scrape response