Fix admin promotions controller

This controller still did not know how what to authorize against, and
wanted to visit a URL that doesn't exist when clicking on a promotion.

This fixes both and adds a test helper, `#click_row` that clicks a row
without selecting it for batch editing purposes.

admin/lib/solidus_admin/testing_support/feature_helpers.rb

@@ -22,6 +22,10 @@ def find_row(text)
         find('table tbody tr', text:)
       end
 
+      def click_row(text)
+        find('table tbody tr td', text: text).click
+      end
+
       def find_row_checkbox(text)
         find_row(text).find('td:first-child input[type="checkbox"]')
       end

promotions/lib/components/admin/solidus_promotions/promotions/index/component.rb

@@ -14,7 +14,7 @@ def search_url
   end
 
   def row_url(promotion)
-    solidus_promotions.admin_promotion_path(promotion)
+    solidus_promotions.edit_admin_promotion_path(promotion)
   end
 
   def page_actions

promotions/spec/system/solidus_promotions/admin/promotions_spec.rb

@@ -32,5 +32,9 @@
     expect(page).to have_content("Promotions were successfully removed.")
     expect(page).not_to have_content("My active Promotion")
     expect(SolidusPromotions::Promotion.count).to eq(3)
+
+    click_row("My future Promotion")
+    expect(page).to have_content("My future Promotion")
+    expect(page).to have_content("Starts at")
   end
 end