CI: Make the publish process seamless

[maelvls]

From #10 (comment).

Goal:

• Add some CI (Github Actions?) with publishing to vsce and ovsx enabled when a tag is created
• I will put OVSX_PAT and VSCE_TOKEN as Github Secret so that everything runs smoothly

[GitMensch]

Likely a good idea in any case: run tests with CI (a separate process/action done before).

In any case it should be decided which route this repo wants to go, for example GitHub Actions are very simple to integrate and well-integrated (one action for each step and "of course", there's a marketplace for those) but hard-wired to GitHub, other options are only hard-wired to git+webhooks and will therefore also work in other places. Travis-CI, Jenkins and other are much more powerful and also can be integrated to GitHub (and everywhere else) - but they are no "one-click" solution.

[I personally prefer to not bound anything to a single "vendor" or place, but I don't have to setup this stuff...]

[maelvls]

same here, I wish I could use tekton or concourse or drone everywhere but I kinda have a limited amount of time to set them up 😅

Would you like to give me a hand on that by opening a PR? I added you as a collaborator of that project, can you access the settings of the project now (e.g. so that you can set github secrets if needed)