OAuth scopes for discount codes

We added new OAuth scopes for managing or viewing Discount Codes. This way you are no longer required to grant scopes for viewing or managing Orders on API clients that are supposed to manage discount codes only.

• [API] Added scope manage_discount_codes:{projectKey} which grants access to all the APIs for creating, updating, deleting and viewing discount codes.
• [API] Added scope view_discount_codes:{projectKey} which grants access to the APIs for retrieving and querying discount codes.