Publish hippo theme via our npm registry instead of maven

Currently Hippo Theme is publised as a maven package, then pulled in as a maven dependency by end projects and then pulled in via the package.json that points to the target folder in that end project.

We want to decrease complexity by publishing Hippo Theme to our npm registry and depending on it in the package.json of end projects directly.

Note: downside is automatic tagging or other maven workflows no longer apply to hippo theme