Centralize logout method; delete OIDC sessions on logout

app/models/openid/Session.model.js

@@ -0,0 +1,17 @@
+const { Model } = require('flitter-orm')
+
+class SessionModel extends Model {
+    static get services() {
+        return [...super.services, 'models']
+    }
+
+    static get schema() {
+        return {
+            payload: {
+                account: String,
+            },
+        }
+    }
+}
+
+module.exports = exports = SessionModel