Add config to deserialize from JSON null value to default primitive value for field of wrapper type

When a JSON null value is deserialized to a primitive int field, the int field is populated with its default value of 0. (I did not check, but I wouldn't be surprised if similar handling is provided when deserializing to other primitive types.)

However, currently when a JSON null value is deserialized to a field of one of the primitive wrapper types, e.g., Integer, then the field is set to null, i.e., it's deserialized as a null reference.

Jackson should provide a deserialization configuration feature to allow the user to specify that the default primitive value is preferred, instead of a null reference. This deserialization feature should operate similarly when deserializing from an empty JSON string.

Brainstorming for a name for this deserialization config feature:

DeserializationConfig.Feature.USE_PRIMITIVE_DEFAULTS_FOR_WRAPPER_NULLS
DeserializationConfig.Feature.USE_PRIMITIVE_DEFAULTS_FOR_EMPTY_WRAPPERS
DeserializationConfig.Feature.PRIMITIVE_DEFAULT_FOR_EMPTY_WRAPPER
DeserializationConfig.Feature.CONVERT_NULL_TO_PRIMITIVE_DEFAULT
DeserializationConfig.Feature.CONVERT_EMPTY_TO_PRIMITIVE_DEFAULT