Add stripeContext to RequestOptions interface (#2354)

* Add stripeContext to interface

* Add to StripeConfig

Author: mbroshi-stripe

types/lib.d.ts

@@ -112,6 +112,11 @@ declare module 'stripe' {
        * An account id on whose behalf you wish to make every request.
        */
       stripeAccount?: string;
+
+      /**
+       * An account on whose behalf you wish to make every request. See https://docs.corp.stripe.com/context for more information.
+       */
+      stripeContext?: string;
     }
 
     export interface RequestOptions {
@@ -131,6 +136,11 @@ declare module 'stripe' {
        */
       stripeAccount?: string;
 
+      /**
+       * An account on whose behalf you wish to make a request. See https://docs.corp.stripe.com/context for more information.
+       */
+      stripeContext?: string;
+
       /**
        * The [API Version](https://stripe.com/docs/upgrades) to use for a given request (e.g., '2020-03-02').
        */