Issue #3114541 by wizonesolutions: Fix coding standards issues

fillpdf.links.task.yml

modules/fillpdf_legacy/fillpdf_legacy.module

...y/src/Plugin/BackendService/LocalServerBackendService.php

modules/fillpdf_legacy/tests/Kernel/LegacyBackendTest.php

src/Component/Utility/FillPdf.php

src/EntityHelperInterface.php

src/FillPdfAdminFormHelperInterface.php

src/FillPdfFileContextAccessControlHandler.php

src/Form/FillPdfFormConfirmFormBase.php

src/Form/FillPdfFormForm.php

src/InputHelper.php

src/Plugin/FillPdfActionPluginBase.php

src/Plugin/PdfBackend/FillPdfServicePdfBackend.php

src/Plugin/PdfBackend/PdftkPdfBackend.php

src/Service/FillPdfAdminFormHelper.php

src/Service/FillPdfContextManager.php

...s/modules/fillpdf_test/src/Plugin/BackendService/Test.php

...pdf_test/src/Plugin/FillPdfBackend/TestFillPdfBackend.php

tests/src/Functional/FillPdfFormDeleteFormTest.php

tests/src/Functional/FillPdfFormDuplicateFormTest.php