Run snippets easily

[davidrsch]

I think a good feature could be making possibly to create or add modules using UI. I have thinked of several possibilities:

• Adding extension on the left bar.
• Adding a button on the file explorer if the extension detect that any file correspond to a shiny app.
• Or adding button besides execute button if extension detects that file correspond to a shiny app.

I think the second one could be the most effective. If a feature like this is added would be also nice to support in the extension other frameworks module or app structure or even allow users define custom app structures or modules.