feat: add support for groups in @Schema and @Operation (fixes #4928)

[balu1225]

• Added groups attribute to @Schema and @operation
• Populated x-groups extension in generated OpenAPI Spec
• Added tests ValidationGroupTest and OperationGroupsTest

Pull Request

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Description

This PR adds support for the groups() attribute in both @Schema and @Operation annotations, allowing them to be serialized into the OpenAPI specification via the x-groups extension.

• Added Class<?>[] groups() default {}; to the @Schema annotation.
• Added Class<?> groups() default Void.class; to the @Operation annotation.
• Updated AnnotationsUtils and ModelResolver in swagger-core to extract groups correctly and serialize them.
• Updated Reader in swagger-jaxrs2 to map the groups property from @Operation to the x-groups extension on the final OpenAPI Operation object.

Fixes: #4928

Type of Change

• 🐛 Bug fix
• ✨ New feature
• ♻️ Refactor (non-breaking change)
• 🧪 Tests
• 📝 Documentation
• 🧹 Chore (build or tooling)

Checklist

• I have added/updated tests as needed
• I have added/updated documentation where applicable
• The PR title is descriptive
• The code builds and passes tests locally
• I have linked related issues (if any)

Screenshots / Additional Context

• Added ValidationGroupTest to swagger-core to verify that x-groups correctly propagates on standard fields and primitives in Schemas.
• Added OperationGroupsTest to swagger-jaxrs2 to verify that x-groups correctly generates as a string for Operations.
• Note for reviewers: PetResourceTest#testSetOfClasses was observed to be failing on upstream master independently of these changes. All feature-specific tests are passing.