DRILL-7999 Base Docker image on maven:3.8.2-jdk-11 and openjdk-11 (#2317)
Add Apache license to .dockerignore.
Make the OpenJDK base image name a variable.
This allows using a single Dockerfile to target a variety of OpenJDK versions.
Base the build container on OpenJDK 8 to maintain compat with JDK >= 8
Remove individual module build commands.
I had hoped these module build layers would be an optimisation but
I now think they result in Maven doing rework rather than building
incrementally.
Add hooks/ dir containing hooks for Docker Hub image builder.
See the committed README for more information.
Add openjdk-8 tag to drill:latest, separate version numbers with hyphen, newest = 14.
Add Apache License to Docker Hub hooks in hooks/
Make the build container base image name an ARG, BUILD_BASE_IMAGE.
Add #!/bin/bash shebang to build hooks.
Base image tags on Docker Hub env var $DOCKER_TAG.
