feat: Implement missing methods in product module and make more tests pass (#6650)

The 2 bigger remaining tasks are:
1. handling prices for variants
2. Handling options (breaking change)

After that all tests should pass on both v1 and v2

integration-tests/factories/simple-product-factory.ts

@@ -48,11 +48,11 @@ export const simpleProductFactory = async (
 
   const manager = dataSource.manager
 
-  const defaultProfile = await manager.findOne(ShippingProfile, {
+  const defaultProfile = (await manager.findOne(ShippingProfile, {
     where: {
       type: ShippingProfileType.DEFAULT,
     },
-  })
+  })) || { id: "default-profile-id" }
 
   const gcProfile = await manager.findOne(ShippingProfile, {
     where: {