PortalsJS github actions workflow that pushes the latest source code to the Playground

[jspenger]

Currently we are manually updating the portalsjs runtime on the Playground. It might be a good idea to have a workflow that does this automatically. Thus, the task is to add a github actions workflow that compiles and uploads the latest PortalsJS version to the Playground. This might also make sense to only be triggered by major version changes, and not continuous/nightly changes.