Update dark theme #4991

Author: Deniz Toprak

resources/scss/theme-dark/form/field/Switch.scss

@@ -2,12 +2,14 @@
     --switchfield-bordercolor-focused: #57B2EF;
     --switchfield-borderwidth-focused: 4px;
     --switchfield-color-knob         : #fff;
+    --switchfield-color-icon-on      : #fff;
+    --switchfield-color-icon-off     : #767676;
+    --switchfield-color-off          : #BDBDBD;
     --switchfield-color-off-disabled : #BDBDBD;
     --switchfield-color-off-hovered  : #9E9E9E;
-    --switchfield-color-off-idle     : #BDBDBD;
+    --switchfield-color-on           : #005A96;
     --switchfield-color-on-disabled  : #005A96;
     --switchfield-color-on-hovered   : #004C7E;
-    --switchfield-color-on-idle      : #005A96;
     --switchfield-height             : 24px;
     --switchfield-knobsize           : 20px;
     --switchfield-opacity-disabled   : .5;