Auto publish extensions after tag/release

[mtxr]

This PR adds the ability to auto publish extensions to Both VS Code Marketplace and Open VSX/Eclipse Foundation registry.

I wasn't able to test this in the repository here, but I tested with an example extension and this code should work as is, though if any chages are required while releasing, don't hesitate to reach out to me.

---

Thank you for your contribution! Before submitting this PR, please make sure:

• [x] Your code builds clean without any errors or warnings
• [x] You have made the needed changes to the docs
• [x] You have written a description of what is the purpose of this pull request above

[mtxr]

@gjsjohnmurray both tokens were added already btw