Add Support for Referencing Files Object in Item Class

[kenzauros]

Motivation

I had to access information of attached files in an item.

Description

A new File class has been added to represent the files associated with an item.

The Item class has been updated to include a Files property, allowing easy access to any files linked to an item.

I have not added the support for editing file objects.

Note

Due to limitations in my local environment, I was unable to run the suite of tests or add new test cases for this feature. I would greatly appreciate it if someone with the appropriate setup could assist with testing or guide me through the process.

I kept the existing code style in the new code but I welcome any feedback or suggestions for improvement.

Thank you for your consideration.