Now that any configuration processing requires schema, we need either a
standalone schema or a provider/provisioner configured with one a lot more
often in tests.
To avoid adding loads of extra boilerplate to the tests, these new helper
functions produce objects pre-configured with a schema that should be
useful for a number of different cases, and can be customized further for
more interesting situations.
A lot of our tests can then just use these pre-defined object and
attribute names in their fixtures in situations where the canned schemas
here are good enough.
