[api][spark] Add REST permission management

[JingsongLi]

Purpose

Add a language-neutral REST management contract for listing, granting, and revoking permissions, and expose it to Spark through catalog procedures. Permission management is provided directly by RESTCatalog without changing the generic Catalog interface.

The REST resource paths are /v1/catalogs/{catalog}/permissions, /grant, and /revoke.

Changes

• Add permission models and public RESTApi management methods.
• Expose permissionManagement() directly from RESTCatalog.
• Add an OpenAPI 3.1 management specification, documentation, and contract validation.
• Add Spark grant_permission, list_permissions, and revoke_permission procedures.
• Add JSON compatibility, REST transport, pagination, policy validation, and Spark integration coverage.

Tests

• mvn -pl paimon-api -Pfast-build -DwildcardSuites=none -Dtest=PermissionManagementJsonTest,RESTPermissionManagementTest,RequestJacksonCompatibilityTest test
• mvn -pl paimon-spark/paimon-spark-ut -am -Pfast-build -Pspark3 -DfailIfNoTests=false -DwildcardSuites=org.apache.paimon.spark.procedure.PermissionProcedureTest -Dtest=none test
• mvn -pl paimon-spark/paimon-spark-ut -am -Pfast-build -Pspark3 -DfailIfNoTests=false -DwildcardSuites=org.apache.paimon.spark.procedure.PermissionProcedureUnsupportedCatalogTest -Dtest=none test
• mvn -pl paimon-api,paimon-core,paimon-spark/paimon-spark-common -Pspark3 -DskipTests validate
• node docs/scripts/validate-rest-openapi.js