completed all the Assignment todos and add some more functionalities

[VI369]

Namaste sir ji ..... This is my second pull request. In the first one #77 I completed all the todos, but the organization wasn't great. I've now organized everything better in this pull request. Take a look, and let me know if anything needs improvement.

Hannji ise complete karne me bahut maja aaya project complete karte samay kai baar chai fata pr ham thahre chai aur code ke ekdam dheath vidiyrthi chhodenge kaise fate chai ko chhan chhan ke kuch kamal ka hi bana. maine user ki tarf soch ke har ek possible way se test bhi kiya or implement bhi...... ab baki aap dekhiye sir aapke reply ka intejaar rahega. assignment sabhi complete kiya aur some features by my own like dislike, deleteOncloudinay. futures me or bhi isme implement karunga

Thanks a ton for this backend playlist. I've learned a bunch!

aur ek baat sir hame bhi hannji bolne ki ab to aadat si ho gai hai 😊