Link previews: add option to enable/disable link previews with exceptions
Suggested initially by Igor: when managing which sites to enable link previews for, we could add the following options:
1) Enable link previews for ALL domains EXCEPT [domain 1, domain 2, domain 3 etc.]
2) Disable link previews for ALL domains EXCEPT [domain 1, domain 2, domain 3 etc.]
This would enable users to apply a general preference for link previews while retaining the option to set exceptions to that rule.
Currently the user can select between:
1) Enable link previews for all sites
2) Enable link previews for [domain]
3) Disable link previews for all sites
4) Disable link previews for [domain]