Implemented dark mode on app

[All3yp]

Hello. 😁
This is my solution to fix issue #12

[acmbot]

Thanks @All3yp, for opening the pull request! 🙌
One of our team-mates will review the pull request soon. ✅

[Samridh29]

@All3yp Toggling between light and dark mode from within the app isn't working. Add toggle button to switch between modes and save them.
Refer to #3 to get an idea of what to do.

[All3yp]

@Samridh29 sorry. I didn't understand at first, but now it's done, with persistent state implemented using UserDefaults. I implemented a UISwitch to change dark and light mode. I also used simple custom Color Assets. I hope you like it when you review it! 😁

[Samridh29]

Hey, @All3yp great work! I found a few bugs while simulating the app. The dark mode implemented is not across all the screens so if you can fix it asap we will be good to go.

[All3yp]

Hi @Samridh29 , I ended up not testing the colors on the details screen and hadn't seen it, I apologize.
Problem solved now. 😁

[Samridh29]

@All3yp great job on implementing dark mode. Looks pretty sick!!

[acmbot]

Congratulations @All3yp, your pull request is merged! 🎉
Thanks for your contributions. 🙌