fix(styling): ms-select highlight bg-color same as nav highlight

packages/common/src/styles/_variables-theme-salesforce.scss

@@ -144,6 +144,7 @@ $slick-multiselect-icon-radio-checked:                        url('data:image/sv
 $slick-multiselect-icon-radio-unchecked:                      url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" fill="transparent" viewBox="0 0 24 24"><path d="M12 3.7c4.6 0 8.3 3.7 8.3 8.3s-3.7 8.3-8.3 8.3-8.3-3.7-8.3-8.3S7.4 3.7 12 3.7z"></path></svg>') !default;
 $slick-multiselect-icon-font-size:                            10px !default;
 $slick-multiselect-icon-radio-border-radius:                  50% !default;
+$slick-multiselect-option-highlight-bg-color:                 #fafafa !default;
 $slick-multiselect-unchecked-opacity:                         0.8 !default;
 $slick-preheader-border-right:                                1px solid #e8e8e8 !default;
 $slick-preheader-grouped-title-justify:                       center !default;