Function create_bandwidth_proof 

pub fn create_bandwidth_proof(
    request: &ChunkRequest,
    provider_peer_id: String,
    provider_public_key: Vec<u8>,
    bytes_transferred: u64,
    provider_signature: Vec<u8>,
    requester_signature: Vec<u8>,
    chunk_hash: Vec<u8>,
    start_timestamp_ms: i64,
    end_timestamp_ms: i64,
    latency_ms: u32,
) -> BandwidthProof

Create a bandwidth proof from a completed transfer.