Use existing dependency schema

[sebhoss]

I'm creating a chart which has a dependency to an existing chart which itself already produces a values.schema.json file. However, the dependency chart does not use helm-schema and instead uses a home grown solution. Unfortunately, the schema generated by helm-schema is not exactly the same as their own and therefore I cannot install my chart even though I am using valid inputs (according to their schema). It would be great if helm-schema has some middle ground between --no-dependencies and analyzing dependencies - maybe something like --use-existing-dependency-schema which just uses an already existing values.schema.json file and merges that with the root chart schema.