(core) New API to collect timing information from formula evaluation.

Summary:
- /timing/start endpoint to start collecting information
- /timing/stop endpoint to stop collecting
- /timing to retrive data gatherd so far

Timings are collected for all columns (including hidden/helpers/system)

Test Plan: Added new

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D4230

app/gen-server/lib/DocApiForwarder.ts

@@ -70,6 +70,9 @@ 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/timing', withDoc);
+    app.use('/api/docs/:docId/timing/start', withDoc);
+    app.use('/api/docs/:docId/timing/stop', withDoc);
     app.use('/api/docs/:docId/forms/:vsId', withDoc);
     app.use('^/api/docs$', withoutDoc);
   }