v0.8.6 Improve vector search performance when deletions are present

Also including a substantial refactor

What's Changed

• refactor: refactor flat search to lance-index by @eddyxu in #1419
• refactor: move encodings to lance-core by @eddyxu in #1425
• feat: expose latest version id api by @chebbyChefNEQ in #1426
• refactor: use function pointers instead of trait objects by @wjones127 in #1424
• feat: automatically convert image to tensors in TF data pipeline by @rok in #1420
• refactor: migrate schema and data types to lance-core by @eddyxu in #1429
• perf: better parallelism in delete vector prefiltering by @westonpace in #1428
• test: fix flaky tests involving tokio::fs::File by @westonpace in #1430
• perf: use selection vector strategy to improve exact knn performance with deletions by @wjones127 in #1418

Full Changelog: v0.8.5...v0.8.6