Support javadoc generation in the build

[binkley]

While working on #483 and fixing javadoc there to raise readability of the PR https://github.com/binkley/modern-java-practices/pull/601, I realized we are not capturing Javadoc for projects.

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A successful project is not just the working code and build pipeline, but includes documentation for others (on your team, other teams, company internal, public). This helps you to:

• Onboard new contributors
• Share code internally
• Share code to the public
• Discuss code goals and APIs with manager roles

Tasks

• [ ] Generate Javadoc from project source using Gradle
• [ ] Generate Javadoc from project source using Maven
• [ ] Provide javadoc both as HTML locally, and as a jar to share with the project
• [ ] Update wiki writing to explain and provide example downloadable resources

[binkley]

The temporary image for the Documentation page is broken:

• It is not transparent
• Unclear on licensing

[binkley]

Example results with ./mvnw clean verify:

🌷 find target -name \*.jar
target/modern-java-practices-0-SNAPSHOT.jar
target/findsecbugs-plugin-1.13.0.jar
target/modern-java-practices-0-SNAPSHOT-test-javadoc.jar
target/modern-java-practices-0-SNAPSHOT-javadoc.jar
target/modern-java-practices-0-SNAPSHOT-jar-with-dependencies.jar

[binkley]

Example results with ./gradle clean build

🌷 find build -name \*.jar
build/libs/modern-java-practices-0-SNAPSHOT.jar
build/libs/modern-java-practices-0-SNAPSHOT-javadoc.jar
build/tmp/.cache/expanded/zip_ff7bf8f04f99dc306508d1c81e47a68b/jacocoagent.jar