(core) Refactor forms implementation

Summary: WIP

Test Plan: Existing tests.

Reviewers: jarek

Reviewed By: jarek

Subscribers: jarek

Differential Revision: https://phab.getgrist.com/D4196

app/gen-server/lib/DocApiForwarder.ts

@@ -70,7 +70,7 @@ export class DocApiForwarder {
     app.use('/api/docs/:docId/webhooks', withDoc);
     app.use('/api/docs/:docId/assistant', withDoc);
     app.use('/api/docs/:docId/sql', withDoc);
-    app.use('/api/docs/:docId/forms/:id', withDoc);
+    app.use('/api/docs/:docId/forms/:vsId', withDoc);
     app.use('^/api/docs$', withoutDoc);
   }