Refactor role mapping structure to use the new role object and update related components

[binoyPeries]

Purpose

• This pull request refactors how roles are referenced in the role entitlement mapping CRUDs, changing from a simple string role_name to a structured role object that supports both name and an optional namespace.
• The changes affect API definitions, backend validation, logging, and frontend components, ensuring consistent handling of role references and improving future extensibility.
• Additionally, the resource hierarchy now uses namespace instead of organization for scoping.
  Related issue: Support Namespace-Level Roles and bindings in OpenChoreo Casbin Engine openchoreo#1442

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