[C++] Describe how to use the C Data Interface

Also provide some general advice (e.g. instead of trying to use the interface types in an application, import the values as soon as they cross the FFI boundary and then work with the regular Arrow types)

No file or test is identified in the issue. Locate the cookbook entry point for the C Data Interface, review how its interface types cross the FFI boundary, and document the recommended use of regular Arrow types afterward; done means the usage guidance and general advice are included.

Written by the indexing model from the issue text.