Translate labels for belongs_to/_form if available (#2590)

Currently, if a model (e.g., `Customer`) has a translation (e.g., `Client`),
the translated label is correctly displayed on the Show page. However,
on the Edit and New pages, the original label (e.g., `Customer`) is
displayed instead of the translated one.

This commit ensures that the translated label for `BelongsTo` fields is
consistently displayed across all pages. Specifically, it modifies the
`belongs_to`/`_form` partial to display the translated label (if available)
instead of the original one.

Fixes #625.

Author: lubieniebieski

app/views/fields/belongs_to/_form.html.erb

@@ -17,7 +17,7 @@ that displays all possible records to associate with.
 %>
 
 <div class="field-unit__label">
-  <%= f.label field.permitted_attribute %>
+  <%= f.label field.attribute, for: "#{f.object_name}_#{field.permitted_attribute}" %>
 </div>
 <div class="field-unit__field">
   <%= f.select(field.permitted_attribute,

spec/features/orders_form_spec.rb

@@ -28,6 +28,26 @@
       expected = order.customer.id.to_s
       expect(find_field("Customer").value).to eq expected
     end
+
+    it "displays translated label when translation for the attribute is available" do
+      order = create(:order)
+      custom_attribute_name = "Client"
+      translations = {
+        activerecord: {
+          attributes: {
+            order: {
+              customer: custom_attribute_name
+            }
+          }
+        }
+      }
+
+      with_translations(:en, translations) do
+        visit edit_admin_order_path(order)
+
+        expect(page).to have_css("label", text: custom_attribute_name)
+      end
+    end
   end
 
   describe "has_many relationships" do
@@ -92,6 +112,26 @@
       end
     end
 
+    it "displays translated label when translation for the attribute is available" do
+      order = create(:order)
+      custom_attribute_name = "Lines"
+      translations = {
+        activerecord: {
+          attributes: {
+            order: {
+              line_items: custom_attribute_name
+            }
+          }
+        }
+      }
+
+      with_translations(:en, translations) do
+        visit edit_admin_order_path(order)
+
+        expect(page).to have_css("label", text: custom_attribute_name)
+      end
+    end
+
     def find_option(associated_model, field_locator)
       field = find_field(field_locator)
       field.find("option", text: displayed(associated_model))