Replace JSON vector store with SQLite

[MackinnonBuck]

This PR removes the JSON vector store and replaces it with a SQLite implementation using Microsoft.SemanticKernel.Connectors.SqliteVec.

Since Microsoft.SemanticKernel.Connectors.SqliteVec isn't shipping publicly yet, I've built Microsoft.SemanticKernel locally and included the generated .nupkgs directly in the repo. This change (41bd61e) will get reverted after the updated Microsoft.SemanticKernel packages ship.

Microsoft Reviewers: Open in CodeFlow

[stephentoub]

I've built Microsoft.SemanticKernel locally and included the generated .nupkgs directly in the repo. This change (41bd61e) will get reverted after the updated Microsoft.SemanticKernel packages ship.

This will add over a mb of binaries to the git history. Are we ok with that? Or did you mean you'll update the pr before it merges?

[jeffhandley]

I applied * NO MERGE *Do not merge this PR as long as this label is present. . We will wait to merge this until the package is published and we can reference it.

[jeffhandley]

This looks great to me, @MackinnonBuck. Nice work! Let's get a review from at least one of @roji or @SteveSandersonMS though, and wait for the NuGet packages to be available before merging.

[roji]

Thanks for pinging me, see below for a few comments.

Note that there will still be a few API changes for GA; some of my comments can already be addressed now, but others can't. So we can do another sync/iteration on this PR (hopefully by Friday everything will be in), and in general only merge after the GA nugets are fully available on nuget.org.

[SteveSandersonMS]

Looks superb - great job!

[jeffhandley]

Just the patch version bum in my comments, and then once @roji approves we're good to go. Nice work, @MackinnonBuck!

[roji]

Looks great @MackinnonBuck! See the one long comment below about doing automatic embedding generation for upsert as well, not just for search. Other than that I think it's ready for merging.

[roji]

Looks great @MackinnonBuck, well done!