Right now, the `zipBaseName` variable in various publish.gradle files
contains the group ID and artifact ID for use by the combiner, however,
they are also duplicated in `artifactGroupId` and `baseArtifactId`,
leading to potential mistakes if they aren't updated together. This
fixes that by adding a new utility function `makeZipBaseName` to
automatically create the right name given a group ID and artifact ID.
This also fixes publishing for thirdparty subprojects, which didn't
update `zipBaseName`.
This will make is so we can get the right artifact to the installer, and we can do it automatically and its guaranteed to match what built the artifacts.
