Function encode_set 

pub fn encode_set(buf: &mut [u8], address: &str, value: &Value) -> usize

Encode a SET message payload (without frame header) Format: msg_type(1) + flags(1) + addr_len(2) + addr + value_data Flags: [has_rev:1][lock:1][unlock:1][has_ttl:1][vtype:4]