Displayed username along with nickname (when they are not identical); Requested and displayed user's avatar; Made the dialog bigger for extended names.
Added a few functions to web_backend (GetImage, GetPlain) to support getting data in multiple content-types.
Added a no_avatar icon for users without avatars.
* qt_themes: replace game_list icons
The original icons were drawn by @BreadFish64 and they do not look that good. So I got some icons in similar styles (black and white) from https://icons8.com to replace the old icons. I'm pretty sure I'm licensed to use them for Citra, by the way.
* icon licenses
* qt_themes: add two colorful themes
These two colorful themes are based on the Default and Dark themes, and contain icons that are colored rather than black and white. These icons come from https://icons8.com and they have been slightly revised by me. I'm pretty sure I was licensed to use them for Citra.
* Add license for icons
In dark theme, it is very hard to see the connected/disconnected icons because they are dark too. So I added two white-coloured icons for the dark theme. This also fixed an issue where theme update does not change the icon on the status bar.
