User search suggestions do not take existing conversations into account

[codedust]

On Android (Element X), when searching for users in the "start chat" menu or when searching for users to invite into a (newly created) room, the search menu does not suggest users that I'm already in contact with.

On iOS and on Desktop, known users are suggested based on recent activity.

In general, it would be nice to keep showing the list of suggested users when entering the first character while searching.