Most of the basic functionality is present, but there are still several
TODO items remaining:

* Rework invoke_nonblock_callback call
* Finish all TODO comments in code files
* Implement cleanupListener
* Add and finish tests
* Fix anything that fails tests
* Switch to Zenoh 1.0 when available

* Remove use to gtest outside of test tree.
* Address error message from zenohcpp library.
* Switch to our temporary zenohcpp conan recipe.

Updating up-cpp version, rewriting pub/sub test to use L2 APIs, updating
the transport to use the revised up-cpp interface from up-cpp#240, and
fixing some general bugs.

Also adds a zenoh config json for use with the tests.

The pre-release up-cpp has critical bugfixes required for this code to
build.

Also makes sure the test configs are captured in the build artifacts so
tests can run in CI.

We know that the current state of this implementaiton does not fully
work. Making this change is a compromise - it keeps the tests active and
running so we can see the output as we work on resolving issues, but
does not prevent us from merging early, incomplete code.

Once this implementation is more stable, we will re-enable this check