Refactoring long method

[victorcaio06]

Refactoring in the withVariantRequests method that is contained in the ShopifyProductUpdateRequest.java file from line 146 to 202.

I'm a student at the federal university of Ceará in Brazil, I'm currently in a course whose final work is to increase contributions to open source projects.

My contribution to this project is in the quality part, I saw that the withVariantRequests method has a Long Method code smell,
so I plan to refactor this method.

Long method found when using the PMD tool.

[victorcaio06]

The code smell has been refactored and remains in a pull request.

Request link: #124

[ryankazokas]

Please keep open until PR is merged.