Merge branch 'feature_Upgrade-to-TYPO3-10' into 'master'

Classes/Updates/UpdatePidToSiteRoot.php

Classes/Updates/UpdateSendingTimes.php

Classes/UserFunc/ExtensionConfiguration.php

Classes/Utility/ExtensionUtility.php

Classes/ViewHelpers/Widget/UriViewHelper.php

Classes/XClass/Form/FormEditorController.php

Classes/XClass/Form/FormManagerController.php

Configuration/Commands.php

Configuration/Services.yaml

Configuration/TCA/tx_sgmail_domain_model_layout.php

Configuration/TCA/tx_sgmail_domain_model_mail.php

Configuration/TCA/tx_sgmail_domain_model_template.php

README.md

Resources/Private/Layouts/Default.html

Resources/Private/Layouts/Newsletter.html

Resources/Private/Partials/Module/DocHeader.html

UPGRADE.md

composer.json

ext_emconf.php

ext_localconf.php