Add new asXxxOr(defaultValue) that returns default value for NullNode instead of coercing

[filiphr]

This adds a new asXxxOr(defaultValue) method which returns default value instead of coercing when using NullNode like we discussed in #5417

[cowtowncoder]

I'm sorry for not following up on this, but just to mention, I am not really keen on adding a significant set of new methods, with fairly narrow scope. Especially since the role of JSON null has not been decided.

I hope to get to follow up on this within couple of days.

Basically -- I'll elaborate later on -- I'd be in favor of slightly different approach of something like

 public JsonNode JsonNode.nullAs(JsonNode);
 public JsonNode JsonNode.nullAs(Supplier<JsonNode>);

where we'd have one or two general-purpose converters for JSON null handling.

[github-actions]

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