Improv/sdl generation

[chrisvdm]

Managing sdl schema is time consuming. Better approach would be to generate schema from Stripe's openAPI Spec. This PR is part one of a larger issue (#117)

API (might need some help here):

• github action triggers script to generate a schema from openAPI.
• script needs a root query OR a list of Stripe Objects as a starting point for the generator.
• Merge generate schema with custom schema (stripeItems)
• schema is saved in sdl file (?) that can be imported into a project

#63