[Zouinek]

Fixes #25363

Adds a useJackson3 option to the jaxrs-spec generator. Jackson 2 stays the default.

• useJackson3 option + cliOption, jacksonPackage property, JsonDeserialize import mapping (moved to tools.jackson.databind in Jackson 3)
• spec/pom.mustache: {{jacksonPackage}} groupIds for the JAX-RS providers, jackson-datatype-jsr310 only for Jackson 2 (built into databind in Jackson 3), Jackson 3 version 3.1.2 (aligned with the CXF generator)
• pojo.mustache: Shape.POJO instead of Shape.OBJECT for Jackson 3 when additional properties are used
• Test testUseJackson3 in JavaJAXRSSpecServerCodegenTest
• Docs regenerated. jaxrs-spec samples regenerated: no changes, since Jackson 2 output is identical.

openliberty/pom.mustache unchanged: it only depends on jackson-annotations, which keeps the com.fasterxml.jackson.core groupId in Jackson 3.

Notes / possible follow-ups:

• USE_JACKSON_3 and the Jackson package constants are now duplicated across several generators. Happy to consolidate them into AbstractJavaCodegen in a follow-up PR.
• 3.1.8 is the latest Jackson 3.1.x; I kept 3.1.2 for consistency with CXF, happy to bump.

Related: #25364 (resteasy client, separate PR).

cc @blaghed

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[Zouinek]

While fixing the ensure-up-to-date failure I noticed that jaxrs-cxf-cdi extends JavaJAXRSSpecServerCodegen, so it inherited the new useJackson3 option.
Its own cxf-cdi/pom.mustache is still hardcoded to Jackson 2 (provider com.fastercml.jackson.jaxrs, Java 1.8), so enabling the option there would generate a project that does not compile.
In 491aee9 i disabled the option for jaxrs-cxf-cdi the same way useJspecify and serializationLibrary are already handled there (removeOption + forced off in processOpts()), covered by testUseJackson3IsIgnored.
If you'd like Jackson 3 support for jaxrs-cxf-cdi too, I'm happy to do that.