[kube-prometheus-stack] Add admission webhook PromQL options

[davidbrusius]

What this PR does / why we need it

Adds prometheusOperator.admissionWebhooks.deployment.promqlOptions to kube-prometheus-stack and renders it as the --promql-options argument on the separate prometheus-operator admission webhook deployment.

This lets users enable PromQL parser options for webhook validation of PrometheusRule resources, e.g. extended-range-selectors, matching the admission webhook CLI support added in prometheus-operator v0.91.0.

Example:

prometheusOperator:
  admissionWebhooks:
    deployment:
      enabled: true
      image:
        tag: v0.91.0
      promqlOptions:
        - extended-range-selectors

Which issue this PR fixes

N/A

Special notes for your reviewer

promqlOptions defaults to an empty list. When set, it requires the prometheus-operator/admission-webhook image to be v0.91.0 or newer.

Local validation run:

• helm dependency build charts/kube-prometheus-stack
• helm lint charts/kube-prometheus-stack
• helm unittest --strict --file 'unittests/**/*.yaml' charts/kube-prometheus-stack
• helm template ... confirmed --promql-options=extended-range-selectors,experimental-functions is rendered

Checklist

• DCO signed
• Chart Version bumped
• Title of the PR starts with chart name (e.g. [prometheus-couchdb-exporter])

[jkroepke]

Thanks