"Resend Purchase Receipt" assumes sending the email was successful

[ashleyfae]

Bug Report

Expected behavior

If I opt to re-send a customer's purchase receipt, and sending the email fails, I expect to see an error message.

Actual behavior

I see an admin notice that says it was successful.

Steps to reproduce the behavior

1. Easiest thing to do is to manually edit EDD_Emails::send() so that it returns false.
2. Click the link via admin payment page to resend a purchase receipt.
3. Note success message.

Information (if a specific version is affected):

PHP Version:

EDD Version (or branch): 2.9.x

WordPress Version:

Any other relevant information:

The edd_email_purchase_receipt() function should return the result of EDD_Emails::send().
Then in edd_resend_purchase_receipt() we should be checking the result of that and changing the edd-message query arg accordingly.