Add tests for running IMDClient synchronously (multithreaded=False) or remove support #83
Description
Is your feature request related to a problem?
Previously, I added support for running IMDClient without ever spinning up another thread. However, we have no tests for this, and it isn't clear that this is ever useful.
Describe the solution you'd like
Decide whether to remove this feature or test it with traj_unchanged tests as with asynchronous mode. Test for both IMDv2 (#82) and IMDv3 streams if synchronous mode is kept.
Related: #75