Add a copy URL button next to each package search result about packagelist

[daveverwer]

Also adding this comment from @jshier from here:

Perhaps the full line that's needed for the Package.swift?

[daveverwer]

@jshier That's really interesting. My initial thought was just the git repository as most people will be pasting it into Xcode, but both could work.

I do think the default should be just the git URL though. As we move forward, the more common use case will start to be people using this with Xcode.