refactor(admin-ui): Make global flex spacer class

packages/admin-ui/src/app/catalog/components/asset-preview/asset-preview.component.scss

@@ -44,6 +44,3 @@
         margin: 0 6px;
     }
 }
-.flex-spacer {
-    flex: 1;
-}

packages/admin-ui/src/app/catalog/components/collection-tree/collection-tree-node.component.scss

@@ -33,10 +33,6 @@
     }
 }
 
-.flex-spacer {
-    flex: 1;
-}
-
 .tree-node {
     display: block;
     background: white;

packages/admin-ui/src/app/catalog/components/product-variants-list/product-variants-list.component.scss

@@ -96,10 +96,6 @@
         margin-top: 22px;
     }
 
-    .flex-spacer {
-        flex: 1;
-    }
-
     .clr-form-control {
         margin-top: 0;
     }

packages/admin-ui/src/styles/theme/_theme.scss

@@ -13,6 +13,10 @@ a:focus, button:focus {
     outline-color: $color-primary-400;
 }
 
+.flex-spacer {
+    flex: 1;
+}
+
 .btn-link.btn-warning {
     color: $color-warning-500;