[Core feature] Expose raw claims in auth IdentityContext

[katrogan]

Motivation: Why do you think this is important?

Now that admin service middleware is customizable, we should expose the raw claims returned by IDP providers for authenticated users to allow for custom authz rules in user's individual flyteadmin deployments.

Goal: What should the final outcome look like, ideally?

Passing along additional claims for use in service middleware should be doable

Describe alternatives you've considered

Not supporting this feature

Propose: Link/Inline OR Additional context

No response

Are you sure this issue hasn't been raised already?

• Yes

Have you read the Code of Conduct?

• Yes