Add `DeserializationFeature.USE_NULL_FOR_MISSING_REFERENCE_VALUES` for selecting `null` vs "empty/absent" value when deserializing missing `Optional` value

[cowtowncoder]

(note: follow-up to #3601, #5335)

As of 3.0.1, handling of "reference types" (java.util.concurrent.atomic.AtomicReference, java.util.Optional) is inconsistent: in case of "missing" (absent) value from incoming JSON, when passed via Constructor:

1. AtomicReference is mapped to null (same as in 2.x and 3.0.0)
2. Optional is mapped to Optional.empty() (same as in 2.x stand-alone module default)

but neither behavior is configurable. (also note that this mapping only matters for Creator-passed properties, including Records -- for Field/Setter settable, absent/missing value is never set).

Let's add a new DeserializationFeature to allow configuring this behavior.

[M-PRANAY]

Could I work on this?If Yes I will paste a skeleton and continue, please reply @cowtowncoder

[cowtowncoder]

@M-PRANAY thank you -- I appreciate the offer -- but I think this is something I need to handle myself.