Combine subproject Javadoc into overall project Javadoc to be published

Right now, Javadoc generated is at the subproject level (e.g. commons, math). We would like an overall Javadoc generated for the entire project (all subprojects combined into one) so we can publish for users to see the whole project.

See this comment from MR #18 !18 (comment 1704769912) for a start on how to do this.