Child resources without parents

[jccisco]

Describe the bug

Given a swagger doc defining a non-compliant parent resource and a compliant sub-resource
When CreateSchemaProviderFromServiceConfiguration is called
Then the resulting provider will have the child resource but not the parent

Scenario: Not compliant parent (2 different URIs for post and put) and a child resource
Given a parent with /v1/cdns/{id} for PUT and /cdn/cdns for POST
When the provider is executed
Then 1 CHILD resource is created --> parent NOT compliant and NOT created but the child IS created and not attached to a GHOST parent
OUTCOME : NOT OK! (BUG)

To Reproduce

Run Test_child_resource_without_parent on https://github.com/dikhan/terraform-provider-openapi/tree/bug/child-resource-with-no-parent

Expected behaviour

The provider should not give access to the child resource if the parent is not terraformable.