[ticket/12759] Allow multiple fields to be loaded via get_option_lang

PHPBB3-12759
[ticket/12759] Cache lang options for all fields while displaying

Previously these would be fetched one field at one time, causing a large number of queries in case there were large number of custom profile fields and/or unique number of users in areas such as viewing topics. Resolve this by caching them at once when generating data for displaying them in templates.

PHPBB3-12759