MacOS and Windows Agents for CDT.cloud Jenkins

Summary

CDT.cloud Blueprint builds a theia electron app with c-related extensions for Linux, Windows, and MacOS. Currently we have no Windows and Mac agents available on the Jenkins: https://ci.eclipse.org/cdt-cloud/

In the end we need the same setup as the Theia project: https://github.com/eclipse-cbi/jiro/blob/master/instances/ecd.theia/jenkins/configuration.yml since the CDT.Cloud Blueprint is based on the Theia Blueprint.