Add JsonNodeFeature.WRITE_PROPERTIES_SORTED for sorting ObjectNode properties on serialization

[cowtowncoder]

(note: inspired by #3963)

So, there are ways for alphabetic output of JSON Object keys, for:

• SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS orders Map keys
• MapperFeature.SORT_PROPERTIES_ALPHABETICALLY orders POJO properties

but there is nothing to force this on ObjectNode (JsonNode subtype). It should be relatively simple to add this, both for general usage and possibly to help with "Canonical JSON" output.