Add a config option to allow empty values or not

When serializing an object, Jackson has some configuration to filter the NULL, empty values, but it seems Jsonb config only includes a `withNullValues` option, and there is no option to ignore empty values, such as:

* empty string, including whitespace, \t\r\n etc.
* empty collection/map
* empty array

No source file or test is named in the issue. Start by reviewing JSON-B configuration and serialization behavior, then define how an empty-value option should treat whitespace-only strings, empty collections and maps, and empty arrays; done means the configuration and its behavior are specified and covered by tests.

Written by the indexing model from the issue text.