[Proposal] Support scale subresource in CRDs

# Summary

Support the `scale` subresource in the different Argo workflows CRDs

# Use Cases

Not having the `scale` subresource makes it difficult to use existing autoscalers like the vertical pod autoscaler. When running Argo in a multi-tenant environment, if a workflow definition does not have the appropriate resource requests and limits set, sudden spikes in CPU usage can cause pods to be evicted both for the workflow causing the spike and other tenants on the cluster. Having the `scale` subresource will allow autoscalers to spin up more nodes to handle any spikes.

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**Message from the maintainers**:

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No files or tests are named. Start by locating the Argo Workflows CRD definitions and the existing Kubernetes resource-subresource handling, then trace how the different workflow CRDs are generated or maintained. Done means the relevant CRDs expose a working scale subresource and coverage verifies the autoscaler-facing behavior.

Written by the indexing model from the issue text.