feat: Add new css class helpers user in activity reaction avatars - M…

…EED-3361 - Meeds-io/MIPs#113 (#741)

Add new css class helpers

(cherry picked from commit d4e31dd)

platform-ui-skin/src/main/webapp/skin/less/core/helpers.less

@@ -144,6 +144,9 @@
 .border-color {
   border: 1px solid @btnBorder !important;
 }
+.border-white {
+  border: 2px solid @white;
+}
 .secondary-border-color {
   border: 1px solid @secondaryColor !important;
 }
@@ -535,7 +538,9 @@
 .hidden-space {
   color: @mediumGrey !important;
 }
-
+.transition-2s {
+  transition: 0.2s;
+}
 .z-index-snackbar {
   z-index: @zindexSnackBar!important;
 }