Add RADIUS authentication modules

[Copilot]

Implements Ansible modules for HashiCorp Vault RADIUS authentication using the hvac library's Radius API.

Modules

• hashivault_radius_config: Configure RADIUS backend (host, secret, port, dial_timeout, nas_port, unregistered_user_policies)
• hashivault_radius_user: Manage RADIUS users and policy assignments (create/update/delete)

Both modules implement idempotency via configuration comparison and support check mode.

Integration

• Added RADIUS to hashivault_auth() for credential-based authentication
• Updated VAULT_AUTHTYPE documentation to include radius

Example Usage

# Configure RADIUS backend
- hashivault_radius_config:
    host: radius.example.com
    secret: "{{ radius_shared_secret }}"
    port: 1812

# Manage user policies
- hashivault_radius_user:
    name: alice
    policies:
      - default
      - app-read
    state: present

Authenticate via environment:

export VAULT_AUTHTYPE=radius
export VAULT_USER=alice
export VAULT_PASSWORD=secret

Test Coverage

• test_radius_config.yml: Configuration idempotency and policy assignments
• test_radius_user.yml: User CRUD operations and policy updates

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add RADIUS modules</issue_title>
<issue_description>Create ansible modules to support RADIUS using https://python-hvac.org/en/stable/source/hvac_api_auth_methods.html#hvac.api.auth_methods.Radius</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add RADIUS modules #500

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[TerryHowe]

@copilot fix broken tests