Support OAUTH2 #2209
Description
OAuth2 / OIDC Access tokens now work
Previously the Rancher OIDC Server issued access tokens that could not be used to authenticate with Rancher.
The expectation was that the ID Token would be used to impersonate the user.
With this change the access token issued for OAuth and OIDC tokens can be used as a standard Bearer token per RFC6750.
With this change comes a change to the OIDCClient mechanism used by the Rancher OIDC Provider - the "allowed scopes" can now be configured in the scopes field which can be used to restrict the scopes that a client can request, if not configured these will default to openid, profile and offline_access.