Adding a right-click context menu inside the workspace

[Azra-Zahin]

Implemented plugin jquery-contextmenu to create a context menu inside the workspace that performs various action on the selected operator(s).

[Azra-Zahin]

**Note: Although the code is working, there is an issue with the way the jQuery plugin is imported into the Angular project, which is why the unit test is failing. This is currently being looked at.

[zuozhiw]

closed in favor of #1647