[TASK] Update extension structure to be compliant to 9LTS

Classes/Controller/BackendController.php

Classes/ViewHelpers/Backend/ControlViewHelper.php

Classes/ViewHelpers/Backend/EditLinkViewHelper.php

Classes/ViewHelpers/Backend/EditOnClickViewHelper.php

Classes/ViewHelpers/Backend/IconViewHelper.php

Classes/ViewHelpers/Backend/Widget/PaginateViewHelper.php

Classes/ViewHelpers/ExtendedIfViewHelper.php

Classes/ViewHelpers/Form/UploadViewHelper.php

Classes/ViewHelpers/PageBrowserViewHelper.php

Classes/ViewHelpers/SetViewHelper.php

Configuration/TCA/Overrides/sys_template.php

Configuration/TCA/Overrides/tt_content.php

Configuration/TCA/tx_sgjobs_domain_model_company.php

Configuration/TCA/tx_sgjobs_domain_model_contact.php

Configuration/TCA/tx_sgjobs_domain_model_department.php

Configuration/TCA/tx_sgjobs_domain_model_job.php

Configuration/TCA/tx_sgjobs_domain_model_job_application.php

Configuration/TypoScript/Backend/constants.typoscript

Configuration/TypoScript/Backend/setup.typoscript

Configuration/TypoScript/Common/setup.typoscript