Upgrade to maven-archetype-plugin 3.3.1

[DavidWhitlock]

Something about version 3.3.1 of the maven-archetype-plugin causes the archetype project integration tests to fail because the grader profile/property appear to be ignored. (That is, the -Pgrader text-based Javadoc doesn't appear to be generated.)

This might be caused by the change for https://issues.apache.org/jira/browse/ARCHETYPE-574

Before we can upgrade to 3.3.1, we'll need to figure out what's wrong here.

[DavidWhitlock]

Interesting. Starting with maven-archetype-plugin version 3.3.1 the archetype-metadata.xml must define <requiredProperties> for each property that is set in the integration test's archetype.properties files.