Fix TransportBuilder for Magento2.3.5 compatibility

[thisisandrew]

Remove di for Message preference, update TransportBuilder to handle attachment, update SenderBuilder to use TransportBuilder

Module latest 12.10 allows PHP7.3 but dev dependencies for testing require <7.3 so no test for this PR. Fix the dev dependencies in the latest version and we can have tests here.

[lingwooc]

In magento 2.3.6 The sales_send_order_invoice_emails cron job throws an exception with this PR.

Run SalesInvoiceSendEmailsCron::execute 
                                                                                  
  Cron-job "sales_send_order_invoice_emails" threw exception ReflectionException                                                                               

In ClassReader.php line 26:
                                                                           
  Class Eadesigndev\Pdfgenerator\Model\Email\SenderBuilder does not exist  

Which is true, because this patch replaces it with a TransportBuilder instance.