Netmonitor resource blocking

[captainbrosset]

The ability to block resources from the Netmonitor landed in Firefox 72 in this bug.

It's an awesome feature that lets users prevent downloading certain resources based on their URLs.
I don't think we've had the chance to write a blog post about this. Creating a short video screencast demo would be great so we can communicate about this more broadly via twitter and other places.

[captainbrosset]

Here is what the feature looks like:

There are 2 main workflows:

• typing in strings in the sidebar to match URLs to be blocked
• or right-clicking on any request in the list and choosing "block URL"