Provide option to choose showing full names in chat

[jordan-violet]

@Lilly

in admin - settings, you need to have enable_names and display_name_on_posts enabled (checked) and then make sure prioritize_username_in_ux is disabled (unchecked). note that this also puts their full name in posts and user card and profile. you can see this in the Meta chat which shows full names

All of the above is already done (double checked to be sure), but chat still shows usernames and not full names:

I wonder if it has anything to do with the custom theme we have from Discourse.