Update shared examples for sorting

If sortable elements have a handle we need to account for it, so that
drag and drop can be performed correctly.

Author: chaimann

admin/lib/solidus_admin/testing_support/shared_examples/moveable.rb

@@ -22,6 +22,7 @@
 RSpec.shared_examples_for "features: sortable" do
   let(:factory_attrs) { {} }
   let(:scope) { "body" }
+  let(:handle) { nil }
 
   before do
     create(factory, displayed_attribute => "First", position: 1, **factory_attrs)
@@ -35,7 +36,10 @@
       expect(find("[data-controller='sortable']").all(:xpath, "./*").last).to have_text("Second")
 
       rows = find("[data-controller='sortable']").all(:xpath, "./*")
-      rows[1].drag_to rows[0]
+      target = rows[0]
+      source = rows[1]
+      source = source.find(handle) if handle
+      source.drag_to target
 
       expect(find("[data-controller='sortable']").all(:xpath, "./*").first).to have_text("Second")
       expect(find("[data-controller='sortable']").all(:xpath, "./*").last).to have_text("First")