Multi selection viewer change

[MarlonCorreia]

Context?

Adding the ability to apply a viewer change to multiple selections at once.

Changes?

• Changed behavior from some functions
  • inspector/set-viewer!
  • applies the viewer change for multiple selected contexts
  • inspector/get-compatible-viewers!
  • Retrieves the intersection of compatible viewers from all selected contexts
  • if nothing is selected, it returns the default viewers
• Add helper functions
  • state/get-all-selected-context
  • Retrieves all the selected contexts
• Apply the logic in two different places on the UI
  • The viewers list, on the bottom left corner
  • The viewer commands from the command pallet
  • portal.ui.commands/select-next-viewer
  • portal.ui.commands/select-prev-viewer
  • portal.ui.commands/select-viewer
  • The viewer commands inside the embedded portal (eg: Calva Notebooks)

How this was tested?

It was tested on the browser and vs-code launcher