Enable CI and Automated Release Management

[rvullriede]

It's unfortunate that this very useful library is not published on Maven Central. Without this only developers who build it locally can use it, which limits its reach.

This PR enabled CI via Github Actions (.github/workflows/maven.yml) and provides an additional actions that automatically releases the artifacts on Maven Central via github's release feature. In order to make this work, you need to follow these steps:

1. signup for maven coordinates to pulish on Maven Central: Publishing Guide. Add you Sonartype credentials as Encrypted Secrets named OSSRH_USERNAME and OSSRH_TOKEN.
2. Create signing keys: https://central.sonatype.org/publish/requirements/gpg/
3. Add your key and key password also as Encrypted Secrets, named OSSRH_GPG_SECRET_KEY and OSSRH_GPG_SECRET_KEY_PASSWORD. See https://gist.github.com/sualeh/ae78dc16123899d7942bc38baba5203c for additional details.

[rvullriede]

If you need help to make this work once the credentials and the signing key are available, I'm happy to support!

[Philipinho]

Thank you for the push. I am working on it.

[Philipinho]

Sorry, I started halfway then and got overwhelmed and didn't check back again. All the secret keys have been added to Github. I will work on finalizing the publishing.