allow @Disposes methods also for producer fields

The current wording of 3.3.7 only allowed disposal methods for producer methods. Producer fields are imo not covered by the wording and cannot get @Disposed

> 3.3.7. Disposer method resolution
> A disposer method is bound to a producer method if:
> • the producer method is declared by the same bean class as the
> disposer method, and
> • the producer method is assignable to the disposed parameter,
> according to the rules of typesafe resolution defined in Section 5.2,
> "Typesafe resolution" (using Section 5.2.3, "Assignability of raw and
> parameterized types").

We should change this and also allow the disposal of producer fields.

This is especially needed in the hindsight of 3.5 Resource fields which currently cannot get disposed.