epee-encoding: add debug module

[hinto-janai]

What

• Adds cuprate_epee_encoding::debug behind feature debug
• Adds code to map T: EpeeObject into debug::EpeeObject which can be formatted with serde_json

Why

To allow sanely debugging binary RPC. This can be used for panic formatting in cuprate-test-rpc as well.

[hinto-janai]

fn main() {
    #[rustfmt::skip]
    let get_blocks_bin_response_default = [
        // header
        0x01, 0x11, 0x01, 0x01, 0x01, 0x01, 0x02, 0x01, 0x01,
        // entry count
        0x14,
        // "start_height": 0
        0x0c, b's', b't', b'a', b'r', b't', b'_', b'h', b'e', b'i', b'g', b'h', b't',
        0x05, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
        // "current_height": 0
        0x0e, b'c', b'u', b'r', b'r', b'e', b'n', b't', b'_', b'h', b'e', b'i', b'g', b'h', b't',
        0x05, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
        // "credits": 0
        0x07, b'c', b'r', b'e', b'd', b'i', b't', b's',
        0x05, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
        // "status": "OK"
        0x06, b's', b't', b'a', b't', b'u', b's', b'\n',
        0x08, b'O', b'K',
        // "untrusted": false
        b'\t', b'u', b'n', b't', b'r', b'u', b's', b't', b'e', b'd',
        0x0b, 0x0
    ];

    let mut bytes =
        cuprate_epee_encoding::to_bytes(cuprate_rpc_types::bin::GetBlocksResponse::default())
            .unwrap();

    assert_eq!(get_blocks_bin_response_default, *bytes);

    println!(
        "{}",
        cuprate_epee_encoding::debug::EpeeObject::new(&mut bytes).unwrap()
    )
}

{
  "credits": 0,
  "current_height": 0,
  "start_height": 0,
  "status": "OK",
  "untrusted": false
}

[SyntheticBird45]

LGTM