Show error messages and highlight for bulk editing

The validation message is on "tax_category", so labels and error messages can use that to show the error state.
But the select field has to be "tax_category_id" to work.

app/views/admin/products_v3/_variant_row.html.haml

@@ -56,6 +56,7 @@
       include_blank: t('.none_tax_category'),
       aria_label: t('.tax_category_field_name'),
       placeholder_value: t('.search_for_tax_categories')))
+  = error_message_on variant, :tax_category
 %td.align-left
   -# empty
 %td.align-right

app/views/spree/admin/variants/_form.html.haml

@@ -65,7 +65,7 @@
       = f.number_field field, value: value, class: 'fullwidth', step: 0.01
 
   .field
-    = f.label :tax_category_id, t(:tax_category)
+    = f.label :tax_category, t(:tax_category), for: :tax_category_id
     = f.collection_select(:tax_category_id, @tax_categories, :id, :name, { include_blank: t(:none) }, { class: 'select2 fullwidth' })
 
   .field