Testing and compatibility with non-blocking back-ends

In this release we did not add any new devices, but focused on better compatibility with back-ends and tests. This was especially important for cold atom circuits, where jobs can easily run for hours and you might not keep the connection between your jupyter notebook and the backend for so long. Main changes include:

• Set up the testing infrastructure with pytest
• Make it possible for devices to listen to non-blocking backends and get a job_id.
• Let devices work in the non-blocking mode such that the user can call the result through the job_id.
• Added an example for the operation of the non-blocking operation.