Add kubevirt_handler integration (#18283)

* initial scaffolding

* report health check metric

* report kubevirt_handler metrics

* update spec.yaml and config/models

* ddev validate

* rename Kubevirt to KubeVirt

* Add E2E tests

* fix CI and e2e tests

* fix manifest.json

* delete dashboard file

* ddev validate ci

* apply suggestions from other PRs

* remove time.sleep from dd_environment env setup

* ddev validate ci

* add DEFAULT_METRIC_LIMIT = 0

* ddev validate labeler --sync

* ddev validate ci

* add basic units to metadata.csv

* add more units in metadata.csv

* send the kubevirt version as metadata

* update README integration link

* fix manifest.json using deleted .info metric

* update README

* fix manifest metrics entries

* update manifest.json e6db76d