Site settings should have a way to be set to default (inherit from global)

[bsclifton]

Description

Issue raised by @bridiver:
If you modify the site settings, including changing them back... they are not updated when you modify the global settings

Steps to Reproduce

1. Visit https://brave.com
2. Open shields. Change cookies to Cookies blocked
3. Change cookies back to Cross-site cookies blocked
4. Visit brave://settings
5. Update global default to Cookies blocked

Actual result:

Site setting for brave.com is retained as Cross-site cookies blocked

Expected result:

There should be an option (for the site) that says Default for when you don't care about the behavior, you just want to inherit the global settings

[bridiver]

other options include adding some kind of "reset" button or setting the value to the current default will automatically reset it