Draft: Add support for reading labels in Rust

$ cargo run --example bfs_labels
2024-01-17T14:25:30+01:00 - INFO - looking up SWHID swh:1:snp:0000000000000000000000000000000000000022 ...
2024-01-17T14:25:30+01:00 - INFO - obtained node ID 1 ...
2024-01-17T14:25:30+01:00 - INFO - visiting graph ...
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:snp:0000000000000000000000000000000000000022
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:rev:0000000000000000000000000000000000000009
2024-01-17T14:25:30+01:00 - DEBUG -     has name "refs/heads/master" and perm None
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:rel:0000000000000000000000000000000000000010
2024-01-17T14:25:30+01:00 - DEBUG -     has name "refs/tags/v1.0" and perm None
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:rel:0000000000000000000000000000000000000021
2024-01-17T14:25:30+01:00 - DEBUG -     has name "refs/tags/v2.0-anonymous" and perm None
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:rev:0000000000000000000000000000000000000009
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:rev:0000000000000000000000000000000000000003
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:dir:0000000000000000000000000000000000000008
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:rel:0000000000000000000000000000000000000010
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:rev:0000000000000000000000000000000000000009
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:rel:0000000000000000000000000000000000000021
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:rev:0000000000000000000000000000000000000018
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:rev:0000000000000000000000000000000000000003
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:dir:0000000000000000000000000000000000000002
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:dir:0000000000000000000000000000000000000008
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:dir:0000000000000000000000000000000000000006
2024-01-17T14:25:30+01:00 - DEBUG -     has name "tests" and perm ExecutableContent
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:cnt:0000000000000000000000000000000000000001
2024-01-17T14:25:30+01:00 - DEBUG -     has name "README.md" and perm Content
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:cnt:0000000000000000000000000000000000000007
2024-01-17T14:25:30+01:00 - DEBUG -     has name "parser.c" and perm Content
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:rev:0000000000000000000000000000000000000018
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:rev:0000000000000000000000000000000000000013
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:dir:0000000000000000000000000000000000000017
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:dir:0000000000000000000000000000000000000002
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:cnt:0000000000000000000000000000000000000001
2024-01-17T14:25:30+01:00 - DEBUG -     has name "README.md" and perm Content
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:dir:0000000000000000000000000000000000000006
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:cnt:0000000000000000000000000000000000000005
2024-01-17T14:25:30+01:00 - DEBUG -     has name "parser.c" and perm Content
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:cnt:0000000000000000000000000000000000000004
2024-01-17T14:25:30+01:00 - DEBUG -     has name "README.md" and perm Content
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:cnt:0000000000000000000000000000000000000001
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:cnt:0000000000000000000000000000000000000007
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:rev:0000000000000000000000000000000000000013
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:rev:0000000000000000000000000000000000000009
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:dir:0000000000000000000000000000000000000012
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:dir:0000000000000000000000000000000000000017
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:dir:0000000000000000000000000000000000000016
2024-01-17T14:25:30+01:00 - DEBUG -     has name "old" and perm ExecutableContent
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:cnt:0000000000000000000000000000000000000014
2024-01-17T14:25:30+01:00 - DEBUG -     has name "TODO.txt" and perm Content
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:cnt:0000000000000000000000000000000000000005
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:cnt:0000000000000000000000000000000000000004
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:dir:0000000000000000000000000000000000000012
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:dir:0000000000000000000000000000000000000008
2024-01-17T14:25:30+01:00 - DEBUG -     has name "oldproject" and perm ExecutableContent
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:cnt:0000000000000000000000000000000000000011
2024-01-17T14:25:30+01:00 - DEBUG -     has name "README.md" and perm Content
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:dir:0000000000000000000000000000000000000016
2024-01-17T14:25:30+01:00 - DEBUG -   Successor: swh:1:cnt:0000000000000000000000000000000000000015
2024-01-17T14:25:30+01:00 - DEBUG -     has name "TODO.txt" and perm Content
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:cnt:0000000000000000000000000000000000000014
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:cnt:0000000000000000000000000000000000000011
2024-01-17T14:25:30+01:00 - DEBUG - swh:1:cnt:0000000000000000000000000000000000000015
2024-01-17T14:25:30+01:00 - INFO - Completed.
2024-01-17T14:25:30+01:00 - INFO - Elapsed: 1ms [19 nodes, 17612.59 nodes/s, 56.78 μs/node]; used/avail/free/total mem N/A/13.06GB/2.85GB/33.45GB
2024-01-17T14:25:30+01:00 - INFO - visit completed after visiting 20 nodes.