Change user findOne endpoint to return more data

Return all the needed data for the user profile page. Return

- favourite drinks, along with the total number of drinkActions for that drink by the user (or sum of millilitre?)
- blood alcohol content - only if the userId is the same as the signed in user - bac is not public!
- sum of money spent each month for the past year

Locate the user findOne endpoint and the data sources for drinkActions, BAC, and spending. Clarify whether favourite drinks should include action counts or millilitres, then define the past-year monthly totals and the signed-in-user check for BAC. Done means the endpoint returns these profile fields with BAC hidden for other users.

Written by the indexing model from the issue text.