Add missing backchannel logout initiators to model type.

[dmarjoram]

Changes

If a client is configured with a certain backchannel logout initiators, any GetClient calls to the management API using the Auth0 SDK will fail with a serialisation exception.

e.g.

"Message": "Error converting value \"email-identifier-changed\" to type 'Auth0.ManagementApi.Models.LogoutInitiators'. 
Path 'oidc_logout.backchannel_logout_initiators.selected_initiators[2]', line 1, position 2385."

The following will cause failures on the latest Auth0 SDK version:

Value	Description
session-revoked	Request was initiated by session deletion.
account-deleted	Request was initiated by an account deletion.
email-identifier-changed	Request was initiated by an email identifier change.

References

The additions to the enumeration come from https://auth0.com/docs/authenticate/login/logout/back-channel-logout/oidc-back-channel-logout-initiators#selected-initiators-property so this PR ensures all initiators currently documented are supported by the SDK.

Testing

• This change adds unit test coverage

• This change adds integration test coverage

• This change has been tested on the latest version of the platform/language or why not

Checklist

• I have read the Auth0 general contribution guidelines

• I have read the Auth0 Code of Conduct

• All existing and new tests complete without errors

[kailash-b]

Hi @dmarjoram 👋

Thanks for taking time and contributing.
We will look into this and get back in about a week.

[kailash-b]

@dmarjoram
Thank you for your time and effort, we have built on top of this PR and merged the changes in #796