Add custom maven enforcer rules to catch banned classes and dependencies

The maven enforcer plugin standard rules aren't sufficient to catch certain issues like:
* An artifact built as an uber/bundled jar (usually with shade plugin) including banned classes.
* An artifact pom that depends on banned dependencies. (bannedDependencies rule provided by enforcer plugin doesn't work always because it doesn't look at the dependency-reduced-pom generated by shade plugin)

Imported from Jira [BEAM-2080](https://issues.apache.org/jira/browse/BEAM-2080). Original Jira may contain additional context.
Reported by: vikasrk.

Start with the original BEAM-2080 Jira issue, then inspect Apache Beam's existing Maven Enforcer configuration; the payload names no repository files or tests. Done means custom checks catch banned classes inside uber or bundled jars and banned dependencies in the artifact POM, including cases involving a shade-generated dependency-reduced-pom.

Written by the indexing model from the issue text.