C++ library example is gone

[cwitting]

Issue

The C++ library example was removed in: #6988
I am using the C++ library, and know of other projects which also are using it, so I think the assumption that it was unused are wrong.

Steps to reproduce

Look in the example folder and see it is not there.

Expectation

The C++ example and library is reintroduced/maintained in the future.

[ctriley]

It seems like the building the C++ library isn't an option in the cmake anymore? I second that removing this was a bad idea.