Add $network support to FireFox

[Alex-302]

Issue Details

uBlockOrigin/uBlock-issues#2792
gorhill/uBlock@c6dedd2

Perhaps the name of the modifier should be changed, as the capabilities in CoreLibs and in Firefox are different.

AdGuard syntax of CoreLibs: https://adguard.com/kb/ru/general/ad-filtering/create-own-filters/#network-modifier

Proposed solution

Add $network support to FireFox

Alternative solution

No response

[DandelionSprout]

I'd normally have proposed to stick to calling it $network instead of $ipaddress, but from my very earliest impressions of the latter, it seems to have more possible parameters that can be added ($script was listed as an example, and I'm betting big that $all is also supported).

[DandelionSprout]

Update: At the time of writing, it appears $ipaddress cannot block sites outright, only the various scripts/images/frames/similar on those sites. So it falls somewhat short of what $network does for non-"Browser Extension" AdGuard versions.