request: also publish to OpenVSX for VSCodium users

[phrohdoh]

https://open-vsx.org/extension/matklad/rust-analyzer
https://github.com/open-vsx/publish-extensions

[SomeoneToIgnore]

Duplicate of #4936

At this stage, our approach is not likely to change due to the reasons described in the same issue, here's the main point, in my opinion:

#4936 (comment)

I propose to continue the discussion there, if you have anything to add.

[phrohdoh]

Apologies for filing a duplicate issue.