Dark mode Implimentation for Desktop

[Shubham-Patel07]

What kind of changes does this PR include?

• Fixes or refactors
• A new Enhancement
• Additional documentation
• Something else

Description

I have Implemented the dark mode for desktop

Relations

Closes #404

Checklist:

• All the contributions made are solely the work of me and my co-authors
• I tested the changes in this PR (if applicable)
• I added unit tests to ensure my change works (when change in Java or on front-end code)
• I added UI tests to ensure my UI changes work (when change in the overall UI, not needed if just adding a challenge)
• The PR passes pre-commit hooks and automated tests

[Shubham-Patel07]

Hi @jgadsden sir,
I have used NativeTheme for the implemented as described in the issue, and please can you help me with the styling such that there is minimal repetition of code.