Support for sending customized format data

[dierbei]

Currently, only u32 types are supported for sending data:

raft-rs/src/server.rs

Lines 644 to 651 in 5853c9f

	let data = u32::from_be_bytes(data[12..16].try_into().unwrap());
	let entry = LogEntry {
	leader_id: self.id,
	server_id: self.id,
	term: self.state.current_term,
	command,
	data,
	};

The effect I'm hoping to achieve is to be able to send any type;

[vaibhawvipul]

great idea.