json schemas for values.yml

[ismith]

Is your feature request related to a problem? Please describe.
Bringing this here for discussion at @bdarfler's request.

I made a change today to the values we specify for our lacework deploy in a particular environment, and on my first attempt, got it wrong.

However, this got caught in our dry run in CI, because lacework's chart contains a values.schema.json, and so the pre-merge dry-run was able to tell me:

Error: UPGRADE FAILED: values don't meet the specifications of the schema(s) in the following chart(s):
lacework-agent:
- image.imagePullSecrets.0: Invalid type. Expected: object, given: string

Which is pretty great! I think we may want to do similar work for our helm charts such that helm upgrade --install --dry-run can tell a developer "hi you've written a values.yml for your config that isn't valid". Like having TypeScript annotations for a library.