Add new Konqi avatars & remove classic, bluestyle, old konqi avatars

Summary: The Konqi mascots are so good, we might as well use them. Our existing avatars are not so good, so I'm removing them.

Test Plan:
{F6920004, size=full}

1. Copy images to `/usr/share/user-manager/avatars/konqui/`
2. Select a Konqi user icon from the gallery in the user_manager KCM.

Reviewers: #vdg, #plasma, ngraham, filipf

Reviewed By: #vdg, ngraham, filipf

Subscribers: filipf, GB_2, ngraham, plasma-devel

Tags: #plasma

Maniphest Tasks: T9910

Differential Revision: https://phabricator.kde.org/D21939