Implement `ParamSerializer::serialize_bytes()`

[abonander]

It could be useful to be able to bind a binary string as a parameter, but ParamSerializer::serialize_bytes() is currently stubbed out:

clickhouse-rs/src/sql/ser.rs

Lines 359 to 364 in ea5f0a1

	unsupported!(
	serialize_map(Option<usize>) -> Result<Impossible>,
	serialize_bytes(&[u8]),
	serialize_unit,
	serialize_unit_struct(&'static str),
	);

I don't really understand why it's not supported, as I assume we could use the same hex escape format as we do for client-side binding:

clickhouse-rs/src/sql/ser.rs

Lines 95 to 98 in ea5f0a1

	fn serialize_bytes(self, value: &[u8]) -> Result {
	escape::hex_bytes(value, self.writer)?;
	Ok(())
	}

It may not be that efficient, but that doesn't seem to be a good reason not to support it at all.