during icon lookup, it uses the first index.theme it finds, (I assume only when the eventually chosen theme with the icon doesn't have an index.theme?) we should include all the standard directories in our theme even if we don't use them.
* chore: extra icons
* chore(extra): remove preferences icons
These can be included with the settings application. I don't think any other applications will use them.
* chore(extra): remove app-library icon
This can be included with the app-library application and others that might want it.
* chore(extra): remove org.gnome.* icons
Not many cosmic applications should require these icons
* chore(extra): remove gnome-*
Cosmic apps shouldn't need these icons
* chore(extra): remove some app icons
Cosmic apps shouldn't need these icons
* chore(extra): remove some positional speaker icons
Most Cosmic apps shouldn't need these icons
* chore(extra): remove graphics icon
Only the graphics applet needs this icon as far as I can tell
* chore(extra): remove window tiled and floating icons
Only the window management applet needs these icons as far as I can tell
* chore(extra): remove airplane mode icons
Only the network applet might need these icons as far as I can tell
* chore(extra): remove bluetooth status icons
Only the bluetooth applet might need these icons as far as I can tell
* chore(extra): remove display brightness status icons
Only the power applet might need these icons as far as I can tell
* chore(extra): remove display notifications status icons
Only the notifications applet might need these icons as far as I can tell
* chore: move bluetooth-symbolic to devices
