Implement OAuth2 server, link oauth:Client and auth::Oauth2Client, implement permission checks

app/models/saml/ServiceProvider.model.js

@@ -1,6 +1,10 @@
 const { Model } = require('flitter-orm')
 
 class ServiceProviderModel extends Model {
+    static get services() {
+        return [...super.services, 'models']
+    }
+
     static get schema() {
         return {
             name: String,
@@ -11,6 +15,11 @@ class ServiceProviderModel extends Model {
         }
     }
 
+    async application() {
+        const Application = this.models.get('Application')
+        return Application.findOne({ active: true, saml_service_provider_ids: this.id })
+    }
+
     to_api() {
         return {
             id: this.id,