(core) deleting queue from single webhook

Summary: Using standard tost notification, message about webhook queue being overflown was added. message is permanent as long as queue is full. Message contains linkt to the webhook setings

Test Plan: two nbrowser test was added - one to check if message is show when queue is full, and second to check if message is dismiss when queue was cleaned.

Reviewers: georgegevoian

Reviewed By: georgegevoian

Subscribers: jarek

Differential Revision: https://phab.getgrist.com/D3929

app/server/lib/DocApi.ts

@@ -763,6 +763,16 @@ export class DocWorkerApi {
 
 
 
+    // Clears a single webhook in the queue for this document.
+    this._app.delete('/api/docs/:docId/webhooks/queue/:webhookId', isOwner,
+      withDoc(async (activeDoc, req, res) => {
+        const webhookId = req.params.webhookId;
+        await activeDoc.clearSingleWebhookQueue(webhookId);
+        await activeDoc.sendWebhookNotification();
+        res.json({success: true});
+      })
+    );
+
     // Lists all webhooks and their current status in the document.
     this._app.get('/api/docs/:docId/webhooks', isOwner,
       withDoc(async (activeDoc, req, res) => {