Add OIDC login support to compliance page

Add Google and Microsoft sign-in buttons to the trust center connect
page, matching the console sign-in experience. The backend OIDC flow
already supports flexible continue URLs, so only the GraphQL schema
and frontend needed changes.

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

pkg/server/api/trust/v1/schema.graphql

@@ -880,10 +880,18 @@ type RecordSigningEventPayload {
   success: Boolean!
 }
 
+type OIDCProviderInfo {
+  name: String!
+  loginURL: String!
+}
+
 type Query {
   viewer: Identity
   node(id: ID!): Node
   currentTrustCenter: TrustCenter
+  oidcProviders: [OIDCProviderInfo!]!
+    @goField(forceResolver: true)
+    @session(required: OPTIONAL)
 }
 
 type Mutation {