Template creator for PDF files

Small patch used for testing in the frontend, but needs a few more adjustments:

• Only expose if pdftk library is installed
• Extend template picker to be able to hide the empty template which does not make sense for PDF files

diff --git a/lib/Listener/RegisterTemplateFileCreatorListener.php b/lib/Listener/RegisterTemplateFileCreatorListener.php
index c538da96d..7f3875270 100644
--- a/lib/Listener/RegisterTemplateFileCreatorListener.php
+++ b/lib/Listener/RegisterTemplateFileCreatorListener.php
@@ -93,5 +93,13 @@ class RegisterTemplateFileCreatorListener implements IEventListener {
                        $odpType->setRatio(1);
                        return $odpType;
                });
+
+               $templateManager->registerTemplateFileCreator(function () use ($appPath) {
+                       $odpType = new TemplateFileCreator('richdocuments', $this->l10n->t('New PDF'), '.pdf');
+                       $odpType->addMimetype('application/pdf');
+                       $odpType->setIconSvgInline(file_get_contents($appPath . '/img/pdf.svg'));
+                       $odpType->setRatio(1);
+                       return $odpType;
+               });
        }
 }

Start in lib/Listener/RegisterTemplateFileCreatorListener.php and review the existing template creator registrations alongside the proposed PDF registration. Check how pdftk availability is detected and how the template picker represents empty templates. Done means PDF creation is exposed only with pdftk installed and the empty template can be hidden for PDF files.