Automate releases of the VSCode debugging extension

Now that #248 has landed, we should ideally automate releasing the extension from GH Actions.

One interesting aspect of that is how to do versioning. My instinct is that we shouldn't tie extension versions to StarlingMonkey's, because while the extension will have to be adapted to changes in StarlingMonkey at times, I would expect it to evolve at its own pace, gaining features and bug fixes independently from StarlingMonkey itself.

Marking this as `help wanted` because I don't plan on working on this myself for the time being, and would be grateful if someone else picked it up.