Is there a way to detect if AI tracking is blocked by browser extension?

**Is your feature request related to a problem? Please describe.**

There is evidence that Application Insights tracking is being blocked by a 3rd party browser extension such as Ad Blocker or Privacy Badger. Is there a method to detect when this is happening?

**Describe the solution you'd like**

When I reproduce the blocking with Privacy Badger I get the following in my JS console --

POST https://dc.services.visualstudio.com/v2/track net::ERR_BLOCKED_BY_CLIENT

I'd like to be able to implement a listener that will fire when this happens in order to give instructions to the user to disable their blocker. This would be ideal to implement on the NotificationManager like so:

const notificationManager = new NotificationManager();
notificationManager.addNotificationListener({
trackingBlocked: events => {
console.log('Tracking is blocked by your browser or browser extension. Events not tracked.. ', events);
},
});
appInsights.loadAppInsights(false, undefined, notificationManager);

**Describe alternatives you've considered**

Intercepting calls to XMLHttpRequest.send. The custom onerror handler is called but the event object does not contain any info about the error --

const savedSend = XMLHttpRequest.prototype.send;
XMLHttpRequest.prototype.send = function (data) {
this.onerror = event => {
console.log('ERROR!..', event, this);
};
savedSend.call(this, data);
};

**Additional context**
Add any other context or screenshots about the feature request here.

Start by reviewing NotificationManager and the XMLHttpRequest.send/onerror path described in the issue, including requests to dc.services.visualstudio.com/v2/track. Determine whether blocked requests can be distinguished reliably; done means defining and implementing the requested tracking-blocked notification behavior, or documenting the browser limitations if detection is not possible.

Written by the indexing model from the issue text.