Add OAuth client branding for trust centers

Serve CIMD logos from dedicated endpoints, expose client metadata
branding through GraphQL, and resolve branding from OAuth clients.

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/server/api/connect/v1/graphql/base.graphql

@@ -38,6 +38,15 @@ type Query {
   oauth2ScopesSupported: [OAuth2Scope!]!
     @goField(forceResolver: true)
     @authentication(required: OPTIONAL)
+  oauthClientBranding(clientId: String): OAuthClientBranding
+    @goField(forceResolver: true)
+    @authentication(required: OPTIONAL)
+}
+
+type OAuthClientBranding {
+  name: String!
+  logo: File
+  clientURL: String
 }
 
 type OIDCProviderInfo {