Add support to Backchannel logout initiators

[ncastrocosta]

Checklist

• I agree to the terms within the Auth0 Code of Conduct.

Describe the problem you'd like to have solved

Add support to allow configure the 'Backchannel logout initiators' of an application client.

Describe the ideal solution

Add the following properties should be added to the auth0_client resource:

• oidc_backchannel_logout_initiators: list of strings. Default: ["idp-logout", "rp-logout"]
• oidc_backchannel_logout_initiators_mode: string (all or custom). Default: custom

If the user chooses for oidc_backchannel_logout_initiators_mode = "all", the oidc_backchannel_logout_initiators must not be present.

This is the behavior I got from Auth API.

Alternatives and current workarounds

No response

Additional context

No response