Add Jar build and update docs, remove uberjar build from documentation (renamed)

As noted in !1 (comment 49205) (and https://phabricator.wikimedia.org/T345073), the addition of the charting library introduced a problem with the uberjar build.

Attempting to fix this problem might introduce issues with dependency licenses. Since our intention is to use the Toolforge Build Service without an uberjar anyway, my suggestion is that we remove the uberjar build entirely using code in this merge request.

This merge also adds the possibility of building a JAR file. The intention is to use it as a replacement for the uberjar as a method of verifying that the application compiles.