Publish to open-vsx.org

Publish to https://open-vsx.org/, and ensure the extension functions as expected with other vscode/theia based editors. Ie. vscodium, gitpod etc.

Start by reviewing the extension's current packaging and publishing setup, then test the extension in open-vsx.org, VSCodium, Gitpod, and other VS Code/Theia-based editors. Done means the extension is published on open-vsx.org and functions as expected in the listed editor environments.

Written by the indexing model from the issue text.