objectbox: give access to underlying store

[loryruta]

Hello, do you think it makes sense to expose the store so to perform more operations on it (e.g. trivially count objects)?

https://github.com/davidmigloz/langchain_dart/blob/d2723976c3f0c36c95115b4b756492e223ffe812/packages/langchain_community/lib/src/vector_stores/objectbox/objectbox.dart#L98

Thanks,

[davidmigloz]

Hey @loryruta,

Sounds fair. I don't see many issues from opening up. I'll do it in the next release.

[loryruta]

Thanks! :)