Added Preloader

[PratikMane0112]

Fixed issue #210

Added a preloader for user attraction for initial few seconds of website

• [X]Feature enhancement

Desktop view -

https://github.com/Muskansahuincredible/StudyNotion-An-Online-Education-Platform/assets/153143167/d62cc706-d701-46db-8ff8-3b53749a7696

Mobile view -

https://github.com/Muskansahuincredible/StudyNotion-An-Online-Education-Platform/assets/153143167/34494dc7-752f-4504-af7a-d35f9218b508

• [X] I have performed a self-review of my code
• [X] I have read and followed the Contribution Guidelines.
• [X] I have tested the changes thoroughly before submitting this pull request.
• [X] I have provided relevant issue numbers, screenshots, and videos after making the changes.
• [X] I have commented my code, particularly in hard-to-understand areas.