Add clone trait for moving value easily

[kakao-jun-e]

To merge the detailed values of RPC into one config value in blake/cuckoo miner

pub struct CuckooConfig {
    pub max_vertex: usize,
    pub max_edge: usize,
    pub cycle_length: usize,

    pub listening_port: u16,
    pub submitting_port: u16,

    pub concurrent_jobs: u16,
}

->

pub struct CuckooConfig {
    pub max_vertex: usize,
    pub max_edge: usize,
    pub cycle_length: usize,

    pub rpc_config: RpcConfig,
    
    pub concurrent_jobs: u16,
}

[sgkim126]

I do not object to this patch, but I think it's right to derive Copy too.

[kakao-jun-e]

Because the String only supports Clone trait. https://doc.rust-lang.org/std/marker/trait.Copy.html#whats-the-difference-between-copy-and-clone