Add storages when constructing extension

[pierredup]

Add storage factories when constructing the container extension, to be compatible with Symfony's Config Builders. Without this change, the config builder doesn't recognise the storage configs.

[what-the-diff]

PR Summary

• Added constructor to PayumExtension class
  A new constructor has been added to improve the structure and organization of the class.
• Refactored load() method
  Some code has been moved from the load() method to the new constructor, making the method cleaner and easier to maintain.