fix(checkbox): add code that got lost in merge

Author: brandyscarney

core/src/components/checkbox/checkbox.common.scss

@@ -152,6 +152,8 @@
  */
 :host(.checkbox-label-placement-end) .checkbox-wrapper {
   flex-direction: row-reverse;
+
+  justify-content: start;
 }
 
 // Label Placement - Fixed
@@ -177,8 +179,6 @@
  */
 :host(.checkbox-label-placement-stacked) .checkbox-wrapper {
   flex-direction: column;
-
-  text-align: center;
 }
 
 :host(.checkbox-label-placement-stacked.checkbox-alignment-start) .label-text-wrapper {

core/src/components/checkbox/checkbox.native.scss

@@ -128,6 +128,10 @@ input {
 // Label Placement - Stacked
 // ----------------------------------------------------------------
 
+:host(.checkbox-label-placement-stacked) .checkbox-wrapper {
+  text-align: center;
+}
+
 :host(.checkbox-label-placement-stacked) .label-text-wrapper {
   @include transform(scale(#{$form-control-label-stacked-scale}));