Add new command to snapshot test

Author: Arkham

packages/features/snapshots/commands.txt

@@ -4,6 +4,7 @@
  app env pull           @shopify/app           
  app env show           @shopify/app           
  app generate extension @shopify/app           
+ app generate schema    @shopify/app           
  app info               @shopify/app           
  auth logout            @shopify/cli           
  commands               @oclif/plugin-commands