text: Title: Option to hide action menu (e.g. "View Source") in Altair plots
  Body: **Is your feature request related to a problem? Please describe.**
  Altair plots always get rendered with the action menu (e.g. "View Source")
  
  **Describe the solution you'd like**
  Include option to hide this part
  
  **Describe alternatives you've considered**
  The alternative is to not use Datapane and rather rely on Altair's embed options (see [here](https://github.com/altair-viz/altair/issues/673))
  
  **Additional context**
  n/a