Add additional test and ability to setFail() more functions

Feature Request

Why

Some tests in /cmd/k3d/ are not returning 100% or close to 100% test coverage, namely hosts.go and root.go. Some functionality is hard to test when we do not have the ability to change/set certain attributes to fail.

Proposed Solution

To fix this, we can make some changes to fake_factory.go and fake apiwrappers to enable this functionality that already exists in the form of .SetFail() bools, and update the tests accordingly.