Add support for ABP filter redirects as mock responses

[bbondy]

Description

This adds support for redirect option ABP filter syntax rules.
This gives us the ability to mock out URLs without doing C++ code changes.
It is expected that this will solve a lot of different webcompat issues.

Steps to Reproduce

1. Go to https://winniethepooh.disney.com/
2. Open DOM inspector
3. Reload the page
4. In the network pane filter for gpt.js

Actual result:

Has the normal content for that URL.

Expected result:

Should have uBlock related content.