As a merchant, I want to read and set inventory source data during import/export so I can manipulate inventory data in bulk and efficiently integrate to other systems.

Background: The current import/export functionality returns only quantity from the default stock and does not allow the merchant to read (on export) or set (on import) inventory data by source. This story enhances both import and export to consider source data.

AC for Import:

• Import under Entity Type=Products
• No change to structure of import file
• Sample File import template contains source example data in qty column when MNI is enabled (different file is provided to user based on MNI enabled/disabled)
• qty column in import file provided by the user can contain any of the following: