UDP Tracker Client: add `scrape` request

[josecelano]

Currently, you can use the UDP Tracker client to make an announce request:

cargo run --bin udp_tracker_client 144.126.245.19:6969 9c38422213e30bff212b30c360d26f9a02136422 
    Finished dev [optimized + debuginfo] target(s) in 0.07s
     Running `target/debug/udp_tracker_client '144.126.245.19:6969' 9c38422213e30bff212b30c360d26f9a02136422`
AnnounceIpv4(
    AnnounceResponse {
        transaction_id: TransactionId(
            -888840697,
        ),
        announce_interval: AnnounceInterval(
            300,
        ),
        leechers: NumberOfPeers(
            0,
        ),
        seeders: NumberOfPeers(
            1,
        ),
        peers: [],
    },
)

I'm going to add the scrape so we can also use it in the Tracker Checker.

cargo run --bin udp_tracker_client announce 144.126.245.19:6969 9c38422213e30bff212b30c360d26f9a02136422 
cargo run --bin udp_tracker_client scrape 144.126.245.19:6969 9c38422213e30bff212b30c360d26f9a02136422 

I'm also going to do some refactors.

Subtasks

• Print JSON instead of debug struct.
• Use anyhow and clap. See HTTP Tracker client.
• scrape command.
• Allow using a domain. Currently, it only allows using an IP.

[josecelano]

The output:

$ cargo run --bin udp_tracker_client scrape 144.126.245.19:6969 9c38422213e30bff212b30c360d26f9a02136422 | jq
    Finished dev [optimized + debuginfo] target(s) in 0.08s
     Running `target/debug/udp_tracker_client scrape '144.126.245.19:6969' 9c38422213e30bff212b30c360d26f9a02136422`

{
  "transaction_id": -888840697,
  "torrent_stats": [
    {
      "seeders": 0,
      "completed": 0,
      "leechers": 0
    }
  ]
}