Adopt changes of Jakarta EE 9

[schabdo]

With Jakarta EE 9 package namespace will change from javax to jakarta. This sounds trivial but introduces a bunch of braking changes within a lot of APIs used by hawkBit:

As a move to the Jakarta EE namespace is a breaking change, all specifications included in the Jakarta EE 9 release MUST release a new major version of the specification document, APIs, and other artifacts

(cf. Jakarta EE 9 Release Plan)

Affected frameworks and versions (by no means exhaustive):

• JPA 3.0 (EclipseLink 3.0)
• Java Bean validation 3.0 (Hibernate validator 7)
• Servlet 4.0 (Jetty 10)
• Spring (N/A #25354)
• JAXB 3.0
• ...