In 3621c01f4b, we implemented
CheckConfig/DiffConfig incorrectly. We should have explicilty added
the handlers (to supress the warnings we were getting) but returned an
error saying the RPC was not implemented. Instead, we just returned
success but passed back bogus data. This was "fine" at the time
because nothing called these methods.
Now that we are actually calling them, returning incorrect values
leads to errors in grpc. To deal with this we do two things:
1. Adjust the implementations in the dynamic provider to correctly
return not implemented. This allows us to pick up the default engine
behavior going forward.
2. Add some code in CheckConfig/DiffConfig that handle the gRPC error
that is returned when calling methods on the dynamic provider and fall
back to the legacy behavior. This means updating your CLI will not
cause issues for existing resources where the SDK has not been
updated.