This allows for a local file based deploy without needed nexus
auth information.
Also signing of packages has been added, either via gradle.properties
or using system properties as a fallback.
The property build.repository allows to configure another endpoint if no
snapshot build is done.
Fix creation of .asc file for tar.gz distribution
Closes#17405
Gradle defaults to tgz extension when tar is compressed. This changes
the tar distribution back to tar.gz. Note that this also means the maven
packaging type is now tar.gz.