Extend Metadata schema

[depsimon]

It'd be great if we could easily extend/override the Metadata schema for the issuers.

I've tried a couple of OIDC configurations (ADB2C & Duende IdentityServer) and both have custom claims_supported, grant_types_supported, response_types_supported etc..

I haven't found an easy way to override that at the moment.

[JasonWeise]

I agree this is really needed as I don't seem to be able to authenticate with OneLogin due to Zod and schema matching issues.

[tonywoode]

my attempts to use this to add Microsoft OIDC SSO suffer the same problem here

[rivertam]

Does this basically mean these providers are simply not supported at all? Dreading recreating OIDC just because the zod schema doesn't match (although maybe the claims/grants need to be actually supported).