feat: add toggle option to wait for node command to complete

[RuiCunhaM]

This PR adds a new option for node commands where we can choose to wait, or not, for the command to complete. It fixes #924 allowing to start GUI applications like Wireshark without blocking the core's GUI.

The default behavior is to wait for completion in order to keep compatibility with previous versions.

Furthermore, I overrode the from_yaml method in NodeCommand to deal with existent configurations that do not have a "wait" value defined. In future versions, if this it no longer a problem, this method can be removed.