Validation errors should include a path

[rgraff]

Is your feature request related to a problem? Please describe.

Validation errors include a fields list that is snakecase, but should instead include a path that is camelCase.

Given a mutation like this:

mutation {
  addOverride(input: {  override: { variantKey: $variantKey}}) { ... }
}

if your variantKey is invalid (InvalidArgument), you'll get a response like this:

%{"data" => %{"addOverride" => %{"errors" => [%{"code" => "invalid_argument", "fields" => ["variant_key"], "message" => "variant key not found"}], "result" => nil}}}

Describe the solution you'd like

You'll want a response like this with path and camelCase

%{"data" => %{"addOverride" => %{"errors" => [%{"code" => "invalid_argument", "path" => ["input", "override", "variantKey"], "message" => "variant key not found"}], "result" => nil}}}

Additional context
I'm unfamiliar with the graphql spec and conventions, there may be a standard here that I'm unaware of.