[Java-JaxRS] Do not depend on jaxb with withXml is false

Created by: selliera

When withXml is false, the generated code should not depend on jaxb classes. Most usages of jaxb annotations are already conditional, but some imports are not. This causes issues when trying to work with recent java runtimes, and not depend on jaxb.

@hiveship, @nickcmaynard @bbdouglas @sreeshas @jfiala @lukoyanov @cbornet @jeff9finger @karismann @Zomzog @lwlee2608 @nmuesch

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