Support other artifacts instead of only docker artifacts

**What is the problem you're trying to solve**
We're currently using Azure Container Registry, but all our external HelmCharts and Dockerfiles are either uploaded through a pipeline or manually. Having them all as cache rules would be nice, so we didn't require any pipelines or manual intervention.

**Describe the solution you'd like**
A clear and concise description of what you want to happen.

Support adding all of our external URLs to the Cache Rule on Azure Container Registries. Right now we can't add all of them because some are either not supported or the artefacts we fetch are not docker artefacts.

A list of registries we use:
- https://azure.github.io/
- https://traefik.github.io/
- https://helm.elastic.co/
- https://open-policy-agent.github.io/
- https://prometheus-community.github.io/
- https://azure.github.io/gitops-connector
- https://charts.jetstack.io/
- https://open-telemetry.github.io/
- https://stakater.github.io/

Would love to be able to use these as external providers for the cache rules.

**Describe alternatives you've considered**
We have an alternative, but the alternative is doing it manually or through the pipelines in Azure DevOps.