Add JsonbAccessorType class annotation

Nobody has claimed this yet.

It would be very convenient to have an analogue to the `@XmlAccessortype` annotation for Jsonb.

Jsonb presently reads fields _plus_ methods. For complex classes having many helper methods this can require extensive `@JsonbTransient` annotation. Presently it is necessary to either write a custom visibility strategy or extensively decorate existing code specifically for JSON, where with XML it is not.

For example, in the following class, we would prefer to simply add a class-level annotation to ignore the _isValid_ method (and all other methods...)

```java
@JsonbAccessorType(JsonbAccessType.FIELD)
public class Foo extends Bar implements Serializable {

public boolean isValid(){}
```

This references

* https://docs.oracle.com/javase/7/docs/api/javax/xml/bind/annotation/XmlAccessorType.html
* https://docs.oracle.com/javase/7/docs/api/javax/xml/bind/annotation/XmlAccessType.html

Start by reviewing the existing JSON-B API annotations and access or visibility strategy, then compare their behavior with the referenced XmlAccessorType and XmlAccessType annotations. Done should provide a class-level JsonbAccessorType and JsonbAccessType.FIELD behavior that excludes methods such as isValid without requiring JsonbTransient annotations.

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