Update github badges

[tortmayr]

What it does

Update README job badges and rename PR workflow to CI

How to test

Follow-ups

Changelog

• This PR should be mentioned in the changelog
• This PR introduces a breaking change (if yes, provide more details below for the changelog and the migration guide)

[martin-fleck-at]

Thank you, Tobias, just a minor nit: When looking at https://github.com/eclipse-glsp/glsp-theia-integration/tree/badges it seems that the backticks for next are not really rendered as you would expect, so I think we should just remove them:

[tortmayr]

Done. Note that the badge in https://github.com/eclipse-glsp/glsp-theia-integration/tree/badges will still reference the old name (With the next).
The badges will update once the publish workflow is executed the next time (with the new name)

[martin-fleck-at]

LGTM!