After the refactoring to integrate HCL2 many of the tests were no longer
using correct types, attribute names, etc.
This is a bulk update of all of the tests to make them compile again, with
minimal changes otherwise. Although the tests now compile, many of them
do not yet pass. The tests will be gradually repaired in subsequent
commits, as we continue to complete the refactoring and retrofit work.
A map value read from a config file will be the default
`[]map[string]interface{}` type decoded from HCL. Since this type can't
be applied to a variable, it's likely that it was a simple map. If
there's a single map value, we can pull that out of the slice during
Eval.
