💄 [#4606] Amend styles for error state

* The modal spacing is a cheeky workaround for tab error icons that would
  otherwise be cut off by the overflow: auto due to the desired scroll
  behaviour inside a form modal.
* The react-select styles ensure the border color of the select is consistent
  with other input types in the django admin style (red border if there are
  validation errors)
* The changelist styles ensure that items in a table row with validation
  errors don't break the (vertical) alignment between them - as soon as
  any has a validation error, its content will be pushed down so we need
  to align to the bottom of the table cell (like in the variables table
  styles).

src/openforms/scss/components/admin/_ReactModal.scss

@@ -53,10 +53,10 @@
     }
   }
 
-  &__header {
-    &:not(:last-child) {
-      margin-bottom: 1em;
-    }
+  &__header + * {
+    // leave room for absolute positioned elements that otherwise get cut off by the
+    // overflow: auto
+    padding-block-start: 1em;
   }
 
   &__close {

src/openforms/scss/components/admin/_changelist.scss

@@ -37,6 +37,10 @@
           padding-right: 1em;
         }
       }
+
+      tr.has-errors td {
+        vertical-align: bottom !important;
+      }
     }
   }
 

src/openforms/scss/vendor/_react-select.scss

@@ -16,5 +16,9 @@
     overflow: visible;
   }
 
+  @at-root .errors &__control {
+    --border-color: var(--error-fg);
+  }
+
   inline-size: clamp(200px, 100%, var(--of-admin-select-max-inline-size));
 }