MAGETWO-95803: Apply coupon code to guests that create accounts after checking out

- Add Automated test

Author: sona-sargsyan

app/code/Magento/Checkout/Test/Mftf/Section/CheckoutSuccessMainSection.xml

@@ -16,6 +16,7 @@
         <element name="orderLink" type="text" selector="a[href*=order_id].order-number" timeout="30"/>
         <element name="orderNumberText" type="text" selector=".checkout-success > p:nth-child(1)"/>
         <element name="continueShoppingButton" type="button" selector=".action.primary.continue" timeout="30"/>
+        <element name="createAnAccount" type="button" selector="input[value='Create an Account']" timeout="30"/>
         <element name="printLink" type="button" selector=".print" timeout="30"/>
     </section>
 </sections>

app/code/Magento/SalesRule/Test/Mftf/Section/AdminCartPriceRulesFormSection.xml

@@ -39,6 +39,7 @@
         <element name="applyDiscountToShippingLabel" type="checkbox" selector="input[name='apply_to_shipping']+label"/>
         <element name="discountAmount" type="input" selector="input[name='discount_amount']"/>
         <element name="discountStep" type="input" selector="input[name='discount_step']"/>
+        <element name="addRewardPoints" type="input" selector="input[name='extension_attributes[reward_points_delta]']"/>
         <element name="freeShipping" type="select" selector="//select[@name='simple_free_shipping']"/>
 
         <!-- Manage Coupon Codes sub-form -->