Handle namespaced ExtraResources properly

[bobh66]

Description of your changes

Use requirements.Resources for namespaced ExtraResources.

Fixes #483

I have:

• Read and followed Crossplane's contribution process.
• Added or updated unit tests for my change.

[doxsch]

Thank you very much for creating this PR. Do you happen to have an approximate release timeline for this change? We would greatly appreciate it, as we are depending on this update.

[adamwg]

One thought on future-proofing, but no objection to merging this as-is either. Not sure if I'm an approver on this repo.

[adamwg]

Would there be any harm in adding all required resources to Resources, but additionally including cluster-scoped resources in ExtraResources? I.e.:

Suggested change

	}
	requirements.Resources[k] = v.ToResourceSelector()
	if v.Namespace == "" {
	requirements.ExtraResources[k] = v.ToResourceSelector() //nolint:staticcheck // need to support Crossplane v1
	}

This would future-proof against ExtraResources support being dropped in some future Crossplane release.

[bobh66]

I did consider that, but I was afraid (maybe unnecessarily) that the GRPC message might get too big if the resource request was duplicated. But maybe that's not possible given the way the resource responses are processed. I'll take a quick look and probably just accept the suggestion.