Eclipse is now maintaining the Adopt OpenJDK project. Due to that change
the base adoptopenjdk image used in the Dockerfile is no longer
supported. This commit is just changing the base image to match the
recommended replacement in the deprecation notice (i.e.
https://hub.docker.com/_/adoptopenjdk).
Fixes the Dockerfiles handling of ANONYMOUS_LOGIN and adds an
EXTRA_ARGS environment variable to allow specifying extra arguments
separate from the username, password and anonymous login options.