feat(source): ENCODE BYTES should allow generated columns

[xiangjinwu]

risingwave/src/frontend/src/handler/create_source.rs

Lines 759 to 766 in e68a7bb

	(Format::Plain, Encode::Bytes) => {
	if cols_from_sql.len() != 1 || cols_from_sql[0].data_type() != &DataType::Bytea {
	return Err(RwError::from(ProtocolError(
	"ENCODE BYTES only accepts one BYTEA type column".to_string(),
	)));
	}
	Ok(cols_from_sql)
	}

Some other format/encode branches above already handle generated columns explicitly.