Docs: Show an example of shellbar with context switcher

[saad-mo]

POs are looking at the documentation site claiming that the context switcher component does not exists. Context switcher is made up of a button, popover, and dropdowns (as shown in the image above). Show an example of the shellbar with context switcher. We can do this on shellbar component page - https://sap.github.io/fundamental/components/shellbar.html