UTF-8 strings in PDF 1.x

[a20dev]

verapdf-arlington 1.29.102 does not report UTF-8 strings as non-conforming in PDF 1.7 documents. Here's a PDF 2.0 document using UTF-8 strings (taken from https://github.com/pdf-association/pdf20examples) with header patched to 1.7:

PDF 2.0 UTF-8 string and annotation (patched).pdf

[bdoubrov]

If the document is 1.7, then any UTF-8 encoded string would be treated as PDFDocEncoded. So, formally there would be no violations of ISO 32000-1 in this case