Update docs for low-level C++ APIs.

[GregoryComer]

📚 The doc issue

After I overhauled the docs, I didn't cover the lower-level C++ APIs very well. We're re-adding the old C++ tutorial, as a stop-gap measure. We should ideally take a holistic look at the native API documentation and cover this in a consistent style.

See #13651 (review).

Suggest a potential alternative/fix

No response

cc @mergennachin @byjlw