Better communicate issues with Vim mode

[martinklepsch]

There are a variety of issues with using Calva with Vim mode as documented on this wiki page. Since most users won't see this wiki page when using Calva first it might make sense to actively warn people when Vim mode is installed.

[PEZ]

Can you test this build for us, @martinklepsch ?

https://1360-125431277-gh.circle-artifacts.com/0/tmp/artifacts/calva-2.0.52-dev-c8fa07b8.vsix

What should happen is:

• If you have the VIM Extension installed:
  • Calva says has a message about the VIM Extension detected and a ling to the documentation.
  • An information box opens with a message that you should see the documentation.
  • The box has a button reading: "Open the docs".
  • Closing the info box w/o clicking the button will show the info box next time Calva is activated and finds the VIM Extension installed. (You might want to test this before clicking the button).
  • Clicking the button opens the user documentation page about using Calva with the Vim Extension
    • The info box should never be seen again.
    • The Calva says message keeps appearing every time Calva activates and finds the VIM Extension.

See https://github.com/BetterThanTomorrow/calva/wiki/Testing-VSIX-Packages if you don't know what to do with the build file. 😄