Respect addBuildEnvironmentEntries for Build-Jdk-Spec

[goutamadwant]

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Fixes #539.

Summary

This makes the JAR plugin pass archive.manifest.addBuildEnvironmentEntries through to Maven Archiver's Build-Jdk-Spec default-entry switch.

When build environment entries are disabled, Build-Jdk-Spec is now omitted along with the other build-environment manifest entries. Normal manifest entries such as Main-Class and the detected Java-Version remain in place.

Tests

• mvn -Prun-its -Dinvoker.test=MJAR-539-build-environment-entries verify
• mvn verify
• mvn -Prun-its verify

[github-actions]

@elharo Please assign appropriate label to PR according to the type of change.