Remove Volley and Move the API logic to viewmodel

[rooparsh]

I see that in followers and following screen, the API has been called by Volley library instead of Retrofit being already there. And moreover, the API is being called in UI itself. It's violating the Clean Code architecture.

[acmbot[bot]]

Thanks @rooparsh, for raising the issue! 🙌 One of our team mates will revert on this soon. ✅

[rooparsh]

Please assign this issue to me, will work on it once the PR Link is merged.

[acmbot[bot]]

This issue has been approved by the owner and is open to solve! @rooparsh got 5 points for this issue! 🎉