[TASK] Removing unnecessary fields (site root etc)

Classes/Controller/MailController.php

Classes/Controller/QueueController.php

Classes/Domain/Model/Mail.php

Classes/Domain/Model/Template.php

Classes/Domain/Repository/MailRepository.php

Classes/Domain/Repository/TemplateRepository.php

Classes/Service/BackendService.php

Configuration/TCA/tx_sgmail_domain_model_mail.php

Configuration/TCA/tx_sgmail_domain_model_template.php

Resources/Private/Templates/Queue/Index.html

ext_tables.sql