Client/gateway functionality

[lfrancke]

As a user of the products in the SDP I'd like an easy way to access and use the deployed products.

An idea on how this could look like:

• We provide a UI (web interface but stackablectl could also be an option) where a user selects a namespace and/or deployed products of Stackable
• Our tool then builds a Dockerfile which will pull in the product images (all versions should already be in the docker repo because they have been deployed) and does a multi-stage build using those products plus a "base" client image to build one master image that contains all of that
• The tool also builds a Pod YAML that pulls in this image plus the relevant ConfigMaps
• Optional: Our tool also builds the image and pushes it to a repo (needs permissions)

[lfrancke]

Concretely what would be needed for the Hadoop based tools is a default log4j.properties. The clients will throw a warning if none is found.

WARNING: log4j.properties is not found. HADOOP_CONF_DIR may be incomplete.