path: prefix url with http:// if not provided when flashing from url

[dfunckt]

@aethernet i think it’s much better to fail with an error if the given argument is a malformed URI than assuming prefixing “http” is the correct answer. It’s the caller’s responsibility to sanitize the argument as they’re the ones dealing with the user.

Also, Etcher allegedly freezes completely when the URL is malformed and that should also be fixed.

[aethernet]

i mostly agree as we don't accept any other protocols but http/https i think it's fair to assume http here

[aethernet]

thinking more about it, you're right let's do that frontend and improve the error handling on EP