j2rs_find_up_simple

6-11x faster than lets_find_up

basic_parent_dir_benchmark/j2rs_find_up_simple
  time:   [8.8047 µs 8.8417 µs 8.8878 µs]
basic_parent_dir_benchmark/lets_find_up
  time:   [55.477 µs 55.839 µs 56.543 µs]

no_result_benchmark/j2rs_find_up_simple_no_result
  time:   [12.947 µs 13.080 µs 13.229 µs]
no_result_benchmark/lets_find_up_no_result
  time:   [527.59 µs 529.45 µs 532.20 µs]