Organising frontend API methods

[jq1836]

Actually, should we lump all api related methods into 2 main files, one for question-service, the other for user-service, instead of maintaining 1 file for 1 method?

Originally posted by @SelwynAng in #174 (comment)

I think that would be a good idea too, that way we have lesser files to maintain and imports will be cleaner. Let's do this in another PR. At the same time, we could also convert all existing ones requests that are still not in the lib directory, e.g. In auth-context. I'm thinking we could also move the fetchers into this file too to make everything cleaner.

Originally posted by @jq1836 in #174 (comment)