Update test command

[a2937]

As of right now, the test command is horribly out of date. It depends on the vscode package which is no longer available. There's a very helpful guide on how to migrate from it over here though.

https://code.visualstudio.com/api/working-with-extensions/testing-extension#migrating-from-vscode

[duckdoom4]

We have not been keeping the unit tests up to date at all to be honest. It's mostly just me and @LuqueDaniel maintaining the extension.

I'm planning on spending some more time on finalizing the new features on the dev branch this month.

All that said, I think it's a great idea to pick this up. If you're interested then feel free to do so. Though feel free to pickup any other feature you'd be interested in. Any help is greatly appreciated! :)