No breaking changes were made to the existing module raft-ann-bench.
The proposal is for migrating functionalities of raft-ann-bench to the refactored module.

Key features of the refactoring:

• Refactor raft-ann-bench.run and make it easier to write tests against. Currently the main() and run_build_and_search() functions in python/raft-ann-bench/src/raft-ann-bench/run/__main__.py are rather difficult to test, as they include quite a bit of parameter parsing and config data processing logic. The refactor would break up the functions into smaller functions.
• Use Pydantic to model the 4 types of config files. This makes config data parsing more robust, as Pydantic performs validation, and it helps remove quite a bit of data parsing code. The 4 types of config files modeled: datasets.yaml as DatasetConfig, algos.yaml as AlgoLibConfig, algo benchmark config (e.g. raft_cagra.yaml) as AlgoConfig, and lastly the benchmark executable's config (e.g. the deprecated deep-image-96-inner.json) as BenchConfig.
• Single CLI entrypoint. Use Typer to organize the CLI commands in a single entrypoint. This would be helpful for incrementally migrating other functionalities, such as raft-ann-bench.plot. Furthermore, documentation for the CLI can be auto-generated with typer raft_ann_bench.cli utils docs --name raft-ann-bench --output raft_ann_benchmarks_cli.md.
• Decouple the ANN executable's parameters from the Python module. Preserve the naming of the ANN executable's parameters (i.e. cpp/bench/ann/src/common/benchmark.hpp), and design the CLI to merely passthrough parameters to the ANN executable (e.g. raft-ann-bench run build).
• Unit tests for the new module.
• Migration tests for ensuring that the new CLI and the old CLI produce the same results.
• Make the Python module importable. The current module name raft-ann-bench cannot be easily imported in Python; replacing it with raft_ann_bench will work.

Closes #2153
Closes #2151
Closes #2150
Closes #2149