Depends on #5492. Review only the last two commits.

This PR updates hnsw_search_graph benchmark to make it convenient to benchmark changes in the compression implementation.

• Uncompressed HNSW links are cached and preserved across benchmark runs, so you don't have to wait each time you run the benchmark.
• Cache file name: target/tmp/segment/hnsw_search_graph/1000000-64-16-100-true-Cosine.links.
  • Since HNSW parameters are part of the file name, the index is properly invalidated if you change them.
  • Caveat: the vectors are not saved. So the results will be garbage if you change the vectors generation code or seed without manually cleaning the cache. Tho I believe that it will be changed rarely (or never).
• HNSW is built in parallel and the progress is shown using indicatif crate.
• Benchmarks are renamed, and a compressed benchmark is added.
  • Old names: hnsw-index-search-group/{hnsw_search,plain_search}.
  • New names: hnsw-search-graph/{uncompressed,compressed,plain}.
• NUM_VECTORS increased from 100_000 to 1_000_000 since wait times are not a problem now.