Site settings should be editable in settings

[bsclifton]

Description

(Brought up by @diracdeltas)
The Muon (browser-laptop) version of Brave does have a way to allow you to clear site-specific settings without having to visit the site. Brave Core unfortunately does not.

Muon would expose this via about:preferences#shields which looked like this:
(under Saved Site Exceptions)

Steps to Reproduce

1. Visit a site (ex: brave.com)
2. Use the shields panel to change the shields settings
3. Go to brave://settings

Actual result:

There is no way to edit shield settings

Expected result:

There should be some way to edit shield settings without having to visit the site

Reproduces how often:

100%

Brave version (brave://version info)

Version 0.61.20 Chromium: 72.0.3626.81 (Official Build) dev (64-bit)

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds? yes