Support checking ghost values

[maxsxu]

What's ghost value?

A ghost value is a value that is not defined in the values.yaml. e.g, the .Values.imagePullSecrets in sn-platform/vault/vault-innitialize.yaml

Why check ghost values?

The ghost values can bring much confusion. The user cannot know the value to be configured by values.yaml, unless he looks at the source code. This also poses a challenge to developers, for example, who knows if adding a feature to values.yaml creates breaking? And it is hard to use the IDE well for indexing, auto-completion, etc.

How to check?

Integrated with GitHub action.