code-analysis: Factor out package versions into Docker build arguments,...

code-analysis: Factor out package versions into Docker build arguments, replace default-jre -> default-jre-headless

Package versions are now factored out as arguments, so that they can even be automatically updated from
iopsys/iopsyswrt by a pipeline.

default-jre has been replaced by default-jre-headless, since this image is designed to run in a container without UI,
so there's no need to pull in graphical dependencies, saving around 300 MB in compressed form:

	REPOSITORY                                                   TAG        IMAGE ID       CREATED          SIZE
	dev.iopsys.eu:5050/iopsys/gitlab-ci-pipeline/code-analysis   iop-8847   aaf075c8e753   23 minutes ago   2.25GB

	REPOSITORY             TAG       IMAGE ID       CREATED        SIZE
	iopsys/code-analysis   latest    ffaa1c3094dc   7 months ago   2.55GB