Add more Yahoo! sites?

[pdehaan]

Currently we only have the one Yahoo! site: https://github.com/mozilla/tippy-top-sites/blob/df4de4b322d3cf0742b6b1527a15bf9f291411d5/top_sites.json#L1395-L1401

We should possibly expand the list to include the search pages and possibly some country subdomains:

• https://search.yahoo.com/
• https://ca.yahoo.com/
• https://ca.search.yahoo.com/