Issue #2359213: WIP Attach generated files to FillPdfFileContext.

fillpdf.permissions.yml

fillpdf.services.yml

src/Controller/HandlePdfController.php

src/Entity/FillPdfFileContext.php

src/FillPdfLinkManipulatorInterface.php

src/OutputHandler.php

src/OutputHandlerInterface.php

src/Plugin/FillPdfActionPlugin/FillPdfDownloadAction.php

src/Plugin/FillPdfActionPlugin/FillPdfSaveAction.php

src/Plugin/FillPdfActionPluginBase.php

src/Plugin/FillPdfActionPluginInterface.php

src/Service/FillPdfContextManager.php

src/Service/FillPdfLinkManipulator.php