Flatten class generation

[sav007]

The issue: with nested class generation approach the nested class name can be too long, for example
UpdateCheckoutShippingAddressQuery.Data.CheckoutShippingAddressUpdate.Checkout.LineItemConnection.LineItemEdge.LineItem.Variant

Proposal: change the way how classes to be generated, so instead of fully nested classes make the structure more flat, for example:

class UpdateCheckoutShippingAddressQuery.Data {
  class CheckoutShippingAddressUpdate {...}
  class Checkout {...}
  class LineItemConnection {...}
  class LineItemEdge {...}
  class LineItem {...}
  class Variant {...}
}

This will reduce the nested levels in class names:

UpdateCheckoutShippingAddressQuery.Data.CheckoutShippingAddressUpdate
UpdateCheckoutShippingAddressQuery.Data.Checkout
UpdateCheckoutShippingAddressQuery.Data.LineItemConnection
UpdateCheckoutShippingAddressQuery.Data.LineItemEdge
UpdateCheckoutShippingAddressQuery.Data.LineItem
UpdateCheckoutShippingAddressQuery.Data.Variant

[sav007]

@BenSchwab @marwanad @digitalbuddha any comments here?

[BenSchwab]

👍 Thanks - this makes the generated code seem much more approachable