provide all images in registry, solve UID conflict

For some use cases it is not possible to build the images when starting the orchestration with docker compose up. E.g.:

• helm deployment for eLTER at MUNI
• docker compose up in VM with limited access to apt repos at LfL
• ...

Here we need to provide pre-built images of init, database, frost, cron-scheduler via a registry.

These images can either be built and pushed in separate repositories or in the orchestration repo - which I would prefer, as it only needs a build stage in the pipeline. It will probably make sense to build frost in a separate repository build pipeline once we include plugins/extensions for authentication instead of only using the base FROST.HTTP.war

Currently the imageas are being built using Dockerfiles to pass the UID from .env as an argument into the image. This is done to avoid conflicts when using local mount binds. If the user has a UID different from 1000 we will have permission conflicts to the mounted directories/files.

Some ideas to fix these permission problems would be to either set the permissions on the files very loose e.g. 666/777 on all mounted files or we need to move mount binds into docker volumes.