* initial cleanup of github workflows
* only run pr-label workflow on push to master
* move docker ci/release summaries to scripts
* add XS label for PR's under 2 lines
* draft test job for Docker CI
* fix & activate Docker CI test job
* add debug step to docker CI
* fix Docker CI test container env
* Docker CI build matrix
* fixup build summaries
* fix pipes in summary
* optimize Dockerfile for layer caching
* more markdown escaping
* add gha cache scopes
* add Docker CI cache clean workflow
