Add support for working with binary indexes.

[aalekhpatel07]

This is an attempt to provide first-class support for Faiss binary indexes consuming the C API (along with a couple of utility functions introduced in facebookresearch/faiss#3318)

Note: #77 got merged so this is in lieu of #79

This should be complete in terms of functionality (at least for a default BinaryIndexImpl) so I'm hoping to learn of any major concerns before continuing down this path and adding the IndexBinaryFlat, IndexBinaryHNSW, etc, concrete impls.

[aalekhpatel07]

Seems like the upstream changes for cloning and creating binary indexes via the C api have landed.

Please let me know if I can contribute towards any other blockers for landing this.

Thanks!

[aalekhpatel07]

So I enabled the CI for these changes and if we bumped upstream to use the latest revision, then the CI test suite continues to pass.

I'm leaning towards waiting for a new release of upstream so we can build against v1.8.1 and hopefully the binary index clone/read changes would be included in that release.

The CI helped discover a couple of bugs and their fixes have now been cherry-picked to this PR.