Support builder pattern like Jackson's @JsonPOJOBuilder

Currently using JSON-B with immutable objects is hardly doable.

@JsonbCreator is only partially helpful here, but makes all parameters required. But also with many parameters the solution starts to smell. Normally one would use the builder pattern in this scenario. However unlike Jackson (@JsonPOJOBuilder) JSON-B does not support it.

Start by reviewing the JSON-B API context around @JsonbCreator and compare the requested behavior with Jackson's @JsonPOJOBuilder. Define the API shape needed to support immutable objects with builder-based deserialization without requiring every constructor parameter, then determine how completion would be verified.

Written by the indexing model from the issue text.