[TASK] Use strings instead of variables for TCA configuration

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

...iguration/TCA/tx_sgjobs_domain_model_experience_level.php

Configuration/TCA/tx_sgjobs_domain_model_job.php

Configuration/TCA/tx_sgjobs_domain_model_job_application.php

ext_localconf.php

ext_tables.php