Function raftstore::store::worker::compact::collect_ranges_need_compact

fn collect_ranges_need_compact(
    engine: &impl KvEngine, 
    ranges: Vec<Vec<u8>>, 
    tombstones_num_threshold: u64, 
    tombstones_percent_threshold: u64
) -> Result<VecDeque<(Vec<u8>, Vec<u8>)>, Error>