CI: Extend Github Release Target

[PhilippvK]

Features to be implemented:

• [x] Pre-fill body of release-drafts with automatically generated changelog from commit messages (See https://github.com/marketplace/actions/get-a-changelog-between-two-references)
• [x] Build MacOS App for Client with bundled JRE (DMG probably does only work on OSX, use IMG as an alternative on UNIX)
• [ ] Build Windows Installer with InnoSetup to bundle JRE with (only if really required, as it requires 32bit wine and does not support much distributions. Have a look at: https://github.com/TheBoegl/innosetup-docker)
• [x] Make Version configuration consistens between artifacts. (Fill templates via Maven if needed)