CI Integration and first Milestone Release

[andi-huber]

• Setup CI - Test build w/ maven
• Integrate w/ dependabot
• Polish the module structure, perhaps move domsupport to companion/applib, etc ..
• Bring in blobstore
• Bring in tukaani-xz (7z support)
• Bring in tooling from Apache Causeway
• Add Java module support (JPMS).
• Setup publishing and do a first 1.0.0-M1 release to maven central

see https://docs.github.com/en/actions/publishing-packages/publishing-java-packages-with-maven