tasks: rework the startTask API

it is now async. change was required to reset the pending flag

src/dashboard.js

@@ -100,7 +100,7 @@ async function startPrepareLocation(domain, auditSource) {
     }
 
     const taskId = await tasks.add(tasks.TASK_PREPARE_DASHBOARD_LOCATION, [ constants.DASHBOARD_SUBDOMAIN, domain, auditSource ]);
-    tasks.startTask(taskId, {});
+    safe(tasks.startTask(taskId, {}), { debug }); // background
 
     return taskId;
 }