Discourse should ignore if a character is accented when doing a search

[rriemann (Robert)]

This bug report from 2017 is related:

Username completition broken for names with accents like Régis

Hello, In my forum, people have real names with all different kind of accents. I tried to use the username completition launched by typing @ to mention a user while writing a response and found that I could not find users by their name if the name contains an é. You can test it on your own. Try to find @zogstrip by typing @ followed by Ré for Régis. The actual username lookup is https://meta.discourse.org/u/search/users?term=r&topic_id=65888&include_groups=true. Note that all characters from t…