Refactor training loop from script to class

[sweep-nightly]

Description

This PR refactors the training loop from a script to a class in order to improve code organization and reusability.

Summary of Changes

• Created a new class called MNISTDataLoader in main.py to encapsulate the functionality of the training loop script.
• Added an __init__ method to the MNISTDataLoader class to initialize the necessary variables for loading and preprocessing the MNIST dataset.
• Updated the Net class in main.py to take an instance of MNISTDataLoader as an argument in its constructor.
• Updated the Net class to use the MNISTDataLoader instance to get the training data instead of directly using the script.
• Updated the import statement in api.py to import the MNISTDataLoader class from main.py.
• Updated the instantiation of the Net class in api.py to pass in an instance of MNISTDataLoader.

Please review and merge this PR to complete the requested refactoring of the training loop.

Fixes #6.

---

🎉 Latest improvements to Sweep:

• Sweep can now passively improve your repository! Check out Rules to learn more.

---

💡 To get Sweep to edit this pull request, you can:

• Comment below, and Sweep can edit the entire PR
• Comment on a file, Sweep will only modify the commented file
• Edit the original issue to get Sweep to recreate the PR from scratch

[sweep-nightly]

Rollback Files For Sweep

• Rollback changes to src/api.py
• Rollback changes to src/main.py

[sweep-nightly]

Apply Sweep Rules to your PR?

• Apply: All docstrings and comments should be up to date.
• Apply: Code should be properly formatted and indented.
• Apply: Variable and function names should be descriptive and follow a consistent naming convention.
• Apply: Imports should be organized and grouped together.
• Apply: There should be no unused imports or variables.
• Apply: Code should be properly commented and include docstrings for functions and classes.