API support for user defined authenticator creation.

[Thisara-Welmilla]

We’re introducing the following API changes to enhance the management of custom authentication extensions, supporting both local and federated types. Based on previous discussions, we decided to treat external authentication service endpoint configurations as primary properties for payloads related to the custom authentication. This results in two distinct models:

• System-defined authenticators: The properties field is a primary property.
• User-defined (custom) authenticators: The endpoint field is a primary property, with no general properties field.

The upcoming API changes include:

• /authenticators/custom/ : New API to create user-defined local authenticators
• /configs/authenticators/{authenticator-id} : response body for the GET request.
• /identity-providers : request body for the PUT request.
• /identity-providers/{identity-provider-id}/federated-authenticators : request body for the PUT request.
• /identity-providers/{identity-provider-id}/federated-authenticators/{federated-authenticator-id} : response and request body for both GET and PUT requests.