Improved support Jupyter notebook and Google Colab

Patches and bug fixes:

• [Viewer] No longer messing up with the queue of tasks in notebooks, so that it is now possible to schedule the execution of other cells and the replay of a simulation is running without causing kernel corruptions
• [Viewer] Do not examine Ipython ports while looking for running Meshcat server to avoid throwing a low-level kernel exception in notebooks, the later not being caught in Google Colab