Add $redirect modifier

[ameshkov]

https://github.com/AdguardTeam/Scriptlets#redirect-resources

Also, after this one is done, we should add new rules to the internal conversion rules:

• Handle $rewrite
• $empty and $mp4 should be converted into $redirect rules

[ameshkov]

We'll need @tvinzz's help with this -- we need a test page on testcases.adguard.com

[sxgunchenko]

core/pull-requests/1485