UX: move "hide profile" checkbox to profile tab (#31095)

This moves the "hide my public profile" checkbox from the
/my/preferences/interface > other section into the top of the
/my/preferences/profile section.

Internal ref - t/146570

spec/system/page_objects/pages/user_preferences_profile.rb

@@ -8,6 +8,14 @@ module PageObjects
         self
       end
 
+      def hide_profile
+        find(".user-hide-profile .pref-hide-profile").click
+      end
+
+      def has_hidden_profile?
+        has_css?(".user-hide-profile .pref-hide-profile input[type=checkbox]:checked")
+      end
+
       def expand_profile_details
         find(".user-main .details .controls .btn-default").click
       end

spec/system/user_page/user_preferences_profile_spec.rb

@@ -19,6 +19,19 @@ describe "User preferences | Profile", type: :system do
     end
   end
 
+  describe "hiding profile" do
+    it "allows user to hide their profile" do
+      SiteSetting.allow_users_to_hide_profile = true
+
+      user_preferences_profile_page.visit(user)
+      user_preferences_profile_page.hide_profile
+      user_preferences_profile_page.save
+      page.refresh
+
+      expect(user_preferences_profile_page).to have_hidden_profile
+    end
+  end
+
   describe "enforcing required fields" do
     before do
       UserRequiredFieldsVersion.create!