Reduce number of API requests for Adtracks

[atrandafir]

The extension makes one request to the API per every adtrack detected.

We should try to group them to make only one at the end of the page load or with some kind of grouped delay to reduce the number of requests.

Also check if there are other requests from the extension with a similar behaviour that could also be improved.

[atrandafir]

Done. Now AdTracks are grouped and processed once every second.

Let's say it detects 120 AdTracks during a 3 seconds page load, well before this change it was making 120 requests to the server.

Now it will do something like:

• one request with 30 items at second 1
• one request with 60 items at second 2
• one request with 30 items at second 3

And if new AdTracks will be detected even if the page finished loading, it will process those too.