argocd HPAs should support user provided metrics

[zswanson]

Is your feature request related to a problem?

ArgoCD helm chart is "hard coded" to use only pod Resource metrics for CPU and memory based on usage vs Requests. Users may have other metrics such as custom prometheus metric aggregations, that they'd rather use. The helm templates for the HPA resources should support user customization of the metric types that are permitted by HPA v2

Related helm chart

argo-cd

Describe the solution you'd like

User supplied values templating of the HPA spec.metrics fields

Describe alternatives you've considered

Currently we are disabling the chart autoscaling parameters and then using the values.extraObjects to define our own HPAs. This works, but due to issues with 'helm templating within helm templating' its hard to make these fully interopt with the rest of the chart so its a very custom solution to each use case.

Additional context

No response