Publish the extension to open-vsx from our own scripts

[jonahgraham]

Ever since open-vsx was created we have relied on scripts provided by them to auto-publish this extension. However that takes some control away from us to publish when we want to.

See EclipseFdn/open-vsx.org#2171 for some background.

[jreineckearm]

This should be addressed by a couple of already merged PRs.
Still need to exercise the first manual release.

• Add Github actions for build and publish to Open-VSIX and Visual Studio Code Marketplace #130
• Update to Node 20 and prettier fix #131
• Bump GH action versions to latest #134
• Remove cdt-gdb-vscode from auto-publish EclipseFdn/publish-extensions#813

[GitMensch]

Done now and can be closed, no?

[jreineckearm]

Closing as I don't see what else is needed here. @jonahgraham , please reopen if I missed something.