They still aren't passing, but this is just enough updating to make the
test program compile successfully after the refactoring related to
provider installation. They are now using the mock provider source offered
by the getproviders package, which is similar but not totally identical
to the idea of mocking the entire installer as these tests used to do, and
so many of them need further adjustment to still be testing what they
intended to test under this new architecture.
Subsequent commits will gradually repair the failing tests.
* command/providers schemas: return empty json object if config parses successfully but no providers found
* command/show (state): return an empty object if state is nil