Support IntelliSense for HelmRelease values

Helm charts can [include JSON schemas](https://helm.sh/docs/topics/charts/#schema-files) for their `values.yaml` (e.g. [traefik](https://github.com/traefik/traefik-helm-chart/blob/master/traefik/values.schema.json) does that).

It would be awesome if the extension could use the schema to provide IntelliSense Code Completion/Linting for the `values` field of `HelmRelease` resource definitions.