Provide a clear error message when cloning fails because a long path on Windows

[alilleybrinker]

Windows by default can often have a too-short limit on total path length, causing Git clones to fail if a path the clone tries to generate is too long.

Right now the error message Hipcheck produces is basically to print Git's error message, which isn't terribly clear or helpful. We should instead detect when this kind of error happens and inform the user that the clone failed due to a path length limit, and guide them through options for how to deal with it.

The main options would either be increasing the path length limit or moving where Hipcheck places clones so it doesn't produce a path that's too long.