Feature/json property in all args constructor

[jpfinne]

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Summary by cubic

Adds Jackson annotations to generated Spring model constructors so Jackson can use property-based deserialization. Applies to all-args or required-args constructors when Jackson is enabled, and skips XML.

• New Features
  • Add @JsonCreator(mode = PROPERTIES) to all-args constructors when x-java-all-args-constructor is used.
  • Add @JsonCreator and @JsonProperty to required-args constructors when all fields are required and no all-args constructor exists.
  • Annotate constructor parameters with @JsonProperty for correct field names, including nullable and container types.
  • Update pojo.mustache, SpringCodegen, tests, and regenerate samples; no annotations added when withXml is true.

^{Written for commit 82d6263. Summary will update on new commits.}