Update Icons

Subdivided the new icons in 3 size categories. As requested by UX
Used the company naming scheme for uniformity and easy recognition.

Known issues:
- Top/Bottom category wasn't taken into account by UX at the time. Since
 this is a recent addition. Both the Walls and Top/Bottom will be updated.
- Cloud/Network connection icons 12px don't render correctly. Due to the
 theme-ing.
- Extruder Icons do not render correctly.

CURA-8010_new_icons

resources/qml/Settings/SettingOptionalExtruder.qml

@@ -105,7 +105,7 @@ SettingItem
             x: control.width - width - control.rightPadding
             y: control.topPadding + Math.round((control.availableHeight - height) / 2)
 
-            source: UM.Theme.getIcon("arrow_bottom")
+            source: UM.Theme.getIcon("ChevronSingleDown")
             width: UM.Theme.getSize("standard_arrow").width
             height: UM.Theme.getSize("standard_arrow").height
             sourceSize.width: width + 5 * screenScaleFactor
@@ -172,7 +172,7 @@ SettingItem
 
                 sourceSize.width: width
                 sourceSize.height: height
-                source: UM.Theme.getIcon("extruder_button")
+                source: UM.Theme.getIcon("Extruder", "30")
                 color: control.color
             }
         }
@@ -237,7 +237,7 @@ SettingItem
 
                     sourceSize.width: width
                     sourceSize.height: height
-                    source: UM.Theme.getIcon("extruder_button")
+                    source: UM.Theme.getIcon("Extruder", "30")
                     color: control.model.getItem(index).color
                 }
             }