Add failing specs for #2306.

Add a renamed resource before adding the original resource and asserting
that both are present in the ResourceCollection.
ResourceCollection#add to act on @resources directly

Using `ResourceCollection#[]` to check for existing resources could
potentially return an incorrect resource and it would wrongly determine
a resource was already in the collection. This change will ensure a resource
added is only considered present if its `resource.resource_name` object
is an exact match in the internal `@resources` hash.

Fixes #2306.
More specs for ResourceCollection#[]
Merge pull request #2456 from zorab47/resource-registration-lookup-fix

ResourceCollection#add to act on internal @resources directly