Migrate JAXB-referring tests to Jakarta EE 9

[tamersaadeh]

Jakarta EE 9 platform renames all the "old" namespaces from javax.xml.bind.* to jakarta.xml.bind.*. This pull request performs this migration so that when Jacakrta EE 9 is released in June 2020 it will be compatible. Initial PR in #407.

[cowtowncoder]

Will most likely not proceed with this change until Jackson 3.0 (master); but even with it need to carefully orchestrate this as the change has high chance of breaking lots of users, use cases.

[cowtowncoder]

As per comments on PR, later changes for Jackson 2.13 allowed this to be done: simple change of annotations would not have worked (since Jackson's annotation introspector needed changes).

Thanks!