Move bio from User to UserProfile

Second part of changes requested in https://meta.discourse.org/t/a-small-ruby-db-refactoring-task/16042: `bio_raw` and `bio_cooked` is moved to UserProfile. All code related to cooking of the bio is now in UserProfile as well. 

One thing I could not figure out is how to set `bio_raw` in `/db/fixtures/005_users.rb`. Also I did not test import scripts, is there some data that can be used to test them (`/script/import_scripts/kunena.rb` uses `bio_raw`)?