Uses parser for embedded font programs, tried before the managed defaults and before parsers registered
earlier: the first parser whose CanParse(ReadOnlySpan<Byte>) accepts a program's bytes reads it, so a parser for a
format the defaults read replaces them, and a parser for a new format adds it.
public PdfOptions UseFontProgramParser(IFontProgramParser parser)
The parser. Shared by every document and thread of the engine: it must keep no state between calls.
ISO 32000-2 §9.9. The font program parser extension point; the managed default reads TrueType programs.