Azure OIDC Providers client ID and client secret cannot be validated on creation

[BruceMacD]

Describe the bug

An invalid client ID and client secret can be set for an Azure OIDC provider.

Expected behavior

We rely on the OIDC provider returning an error response from the OIDC token endpoint when validating that a provider exists, but Azure returns a 200 OK with some error details in a web page. It does not honor the Accept header either.

Screenshots

Additional context

We will probably have to look at alternative ways to verify Azure, if it is possible.