Backend -- Improving File Structure

[haidyelnahass]

Feature description

**Backend Improvement Suggestions: ** 1- Adding better file structure (seperating logic into controllers instead of being in routes folder) 2- adding model/routes/controller for whiteboard to help a user save notes or fetch old notes or anything that was written on the whiteboard

Also I would like to suggest that routes should be named in a better way, for instance, it should be in snake case instead of camel case, also we could use 'sign-up' instead of 'registerUser' etc..

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