feat(prisma): export typeDefs (#53)

Closes prisma-labs/prisma-binding#91

Author: ojkelly

src/generators/prisma-ts.ts

@@ -26,7 +26,7 @@ function renderHeader(schema: string): string {
   return `import { Prisma as BasePrisma, BasePrismaOptions } from 'prisma-binding'
 import { GraphQLResolveInfo } from 'graphql'
 
-const typeDefs = \`
+export const typeDefs = \`
 ${schema}\``
 }
 
@@ -65,4 +65,4 @@ ${renderMainSubscriptionMethodFields(subscriptionType.getFields())}
       : ''
   }
 }`
-}
+}