refactor(rust/core): moved adbc traits to sync mod

[if0ne]

A small step toward implementing #3714

[if0ne]

СС @lidavidm

[lidavidm]

While I'm not opposed to breaking changes, I still feel it would be least disruptive to have the async traits in their own (new) module, rather than the sync traits

[lidavidm]

Or is this just to clean up lib.rs while keeping public import paths the same?

[if0ne]

Clean up lib.rs. I'm re-exporting trais from the sync module

https://github.com/if0ne/arrow-adbc/blob/bf2f871b2b2264dbbb0fcb1fac66c79f1826e431/rust/core/src/lib.rs#L48

[lidavidm]

@felipecrv@eitsupi any concerns?

[eitsupi]

There doesn't seem to be any problem with this movement 🚀

[felipecrv]

@felipecrv@eitsupi any concerns?

I would prefer sync to be the default (no namespace), but that is a minority take.

[lidavidm]

@felipecrv@eitsupi any concerns?

I would prefer sync to be the default (no namespace), but that is a minority take.

Right, this doesn't change anything, since the submodule's contents are re-exported. I do think that even when we add async traits, those should not be at the crate root but should be namespaced (and we can keep sync as the default).