[ENH] Make Rust/C++ FFI error handling robust

[HammadB]

Description of changes

Summarize the changes made by this PR.

• Improvements & Bug fixes
  • Introduces a mechanism to propagate errors from C++ into rust by catching errors in the bindings and then populating a thread_local variable.
  • Build the c++ code automatically on change
  • Propagate new errors up through the codebase
  • Coalesce shared functionality in rust hnsw tests
  • the c++ bindings were creating errors, but not throwing them, this path is purely defensive so it was never excercised, this fixes that.
• New functionality
  • None

Test plan

How are these changes tested?
Added a new test to test add() errors

• Tests pass locally with pytest for python, yarn test for js, cargo test for rust

Documentation Changes

None

[github-actions]

Reviewer Checklist

Please leverage this checklist to ensure your code review is thorough before approving

Testing, Bugs, Errors, Logs, Documentation

• Can you think of any use case in which the code does not behave as intended? Have they been tested?
• Can you think of any inputs or external events that could break the code? Is user input validated and safe? Have they been tested?
• If appropriate, are there adequate property based tests?
• If appropriate, are there adequate unit tests?
• Should any logging, debugging, tracing information be added or removed?
• Are error messages user-friendly?
• Have all documentation changes needed been made?
• Have all non-obvious changes been commented?

System Compatibility

• Are there any potential impacts on other parts of the system or backward compatibility?
• Does this change intersect with any items on our roadmap, and if so, is there a plan for fitting them together?

Quality

• Is this code of a unexpectedly high quality (Readability, Modularity, Intuitiveness)

[atroyn]

was this untested behavior?

[HammadB]

Not really, this path was never hit, it should have been removed, we always set k to min(k, len()) in calling code.

[atroyn]

maybe it pays to be defensive here, I haven't looked but is there any chance of UB if we do send k > res.size() ?

[HammadB]

nope, hnsw handles it fine, it just underpopulates the results, this was carried over from the hnsw bindings for python that choose to explicitly throw. We are changing the contract from the python bindings that it is OK to return < K results

[codetheweb]

neat