Add ZLS to the Open VSX Registry

[BinaryWarlock]

https://open-vsx.org/

The VSCodium fork uses this repository instead of Microsoft's, it would be nice to publish it there.

[markfirmware]

This would also be helpful for gitpod

https://www.gitpod.io/blog/open-vsx/#open-vsx

[daenney]

There's a GitHub Action to automate releases to both the VS Code marketplace, as well as the OpenVSX registry: https://github.com/marketplace/actions/publish-vs-code-extension

[SuperAuguste]

Good to know, thanks daenney.