Misleading error pointing to spec.initProvider when required parameters are not provided

[turkenh]

What happened?

We are getting misleading/confusing errors when we don't provide a top-level required parameter indicating as if it should have been set under spec.initProvider.

See related discussion: crossplane-contrib/provider-upjet-azure#535 (comment)

How can we reproduce it?

Trying to create the following manifest:

apiVersion: eventhub.azure.upbound.io/v1beta1
kind: EventHub
metadata:
  name: example-eventhub
spec:
  forProvider: {}

Fails with:

The EventHub "example-eventhub" is invalid:
* spec: Invalid value: "object": no such key: initProvider evaluating rule: messageRetention is a required parameter
* spec: Invalid value: "object": no such key: initProvider evaluating rule: partitionCount is a required parameter

[lsviben]

This should fix it: #274