[ticket/12890] Search by custom profile fields for members

Still a work in progress, requires work for field-specific scenarios such as the date field and requires work on finishing the templates for memberlist

[PHPBB3-12890](https://tracker.phpbb.com/browse/PHPBB3-12890)


I'm not sure what you mean by this? Do you mean make it depend on \phpbb\db\driver\driver?