Support Sigv4 authentication for remote write in OCP monitoring

Copy/paste from [_https://github.com/openshift-cs/managed-openshift/issues/60_]

Which service is this feature request for?
OpenShift Dedicated and Red Hat OpenShift Service on AWS

What are you trying to do?
Allow ROSA/OSD to integrate with AWS Managed Prometheus.

Describe the solution you'd like
Remote-write of metrics is supported in OpenShift but it does not work with AWS Managed Prometheus since AWS Managed Prometheus requires AWS SigV4 auth.

• Note that Prometheus supports AWS SigV4 since v2.26 and OpenShift 4.9 uses v2.29.

Describe alternatives you've considered
There is the workaround to use the "AWS SigV4 Proxy" but I'd think this is not properly supported by RH.
https://mobb.ninja/docs/rosa/cluster-metrics-to-aws-prometheus/

Additional context
The customer wants to use an open and portable solution to centralize metrics storage and analysis. If they also deploy to other clouds, they don't want to have to re-configure. Since most clouds offer a Prometheus service (or it's easy to self-manage Prometheus), app migration should be simplified.