Multiple origin support in entries

[sandysage]

@changecourse I had a good chat with @jimporter about the inverse of multiple entries as seen in #495.

For those of us who have the same LDAP creds for both Mozilla.com and Mozilla.org, do we want to consider an option in the entry details to have multiple website addresses so that it pops up as a suggestion on different domains?

This isn't a hard dependency for fill, which is why I'm opening this as it's own ticket for discussion.

It's worth noting that without some consideration here users using an SSO account wouldn't have a good experience.

[jimporter]

For what it's worth, multi-origin support is really common in password managers (for exactly this reason), and we already have backend support for it in the datastore. We just don't have UI for it yet.