* command: refactor testBackendState to write states.State
testBackendState was using the older terraform.State format, which is no
longer sufficient for most tests since the state upgrader does not
encode provider FQNs automatically. Users will run `terraform
0.13upgrade` to update their state to include provider FQNs in
resources, but tests need to use the modern state format instead of
relying on the automatic upgrade.
* plan tests passing
* graph tests passing
* json packages test update
* command test updates
* update show test fixtures
* state show tests passing
This is a stepping-stone PR for the provider source project. In this PR
"legcay-stype" FQNs are created from the provider name string. Future
work involves encoding the FQN directly in the AbsProviderConfig and
removing the calls to addrs.NewLegacyProvider().
* 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