Add PdfViewerExt component

• new component UPdfViewerExt - advanced PDF viewer with features:
  • manage toolbar buttons; - add a watermark to a PDF document;
  • highlight key-value pairs, tables and annotations in the PDF document;
  • add and remove annotations in a PDF document;
  • search for text in a PDF document (with highlighting);

Can be enabled by set ubConfig.uiSettings.adminUI.pdfViewer.extendedPdfViewer: true. Recommended config section with ENV variables is:

"uiSettings": {
  "adminUI": {
    //....
    "pdfViewer": {
        "uriSuffix": "%UB_PDF_URI_SUFFIX||#view=FitH%",
        "extendedPdfViewer": %UB_USE_EXTENDED_PDF_VIEWER||false%,
        "allowPrint": %UB_PDF_ALLOW_PRINT||true%,
        "allowDownload": %UB_PDF_ALLOW_DOWNLOAD||true%,
        "allowAnnotations": %UB_PDF_ALLOW_ANNOTANION||false%
    }
  }
}