Added "Add Folder" and "Add Divider" Button Functionality

[ishaansathaye]

• Made backend requests to get the dividers for a user in the dropdown for dividers
• Made backend post request to send the new folder created that is now associated with a divider into the user
• Took care of an edge case where the fields are empty

[ishaansathaye]

• Fixed some edge cases with the code
• Should work as intended now

[ishaansathaye]

• Finished adding divider functionality
• We are now able to add dividers and folders through the app for users (edge cases such as none entered are in place too)

[ravippanchal]

LGTM