[BUGFIX] Fix ViewHelpers and deprecated stuff for the backend module

Classes/Command/SendMailCommandController.php

Classes/Controller/MailController.php

Classes/Controller/QueueController.php

Classes/Service/BackendService.php

Classes/ViewHelpers/AddJavaScriptFileViewHelper.php

Classes/ViewHelpers/Backend/ControlViewHelper.php

Classes/ViewHelpers/Backend/EditOnClickViewHelper.php

Classes/ViewHelpers/Backend/IconViewHelper.php

Classes/ViewHelpers/Backend/Widget/PaginateViewHelper.php

Classes/ViewHelpers/Be/Menus/ActionMenuItemViewHelper.php

.../ViewHelpers/Be/Menus/ActionMenuOptionGroupViewHelper.php

Classes/ViewHelpers/ExtendedIfViewHelper.php

Classes/ViewHelpers/InlineLanguageLabelsViewHelper.php

Classes/ViewHelpers/IsArrayViewHelper.php

Classes/ViewHelpers/SetViewHelper.php

Classes/ViewHelpers/Widget/UriViewHelper.php

Resources/Private/Layouts/Default.html

Resources/Private/Layouts/NoMenu.html

Resources/Private/Layouts/Queue.html

composer.json