OpenSystemsDevelopment / qpdf

This reverts commit 56c923d1096b0317d978bdadeb44e8198053286c.

This commit breaks pikepdf.

Recognise that JSON objects are effectively shared pointers to JSON_value.

Refactor creation of object descriptions

Eliminate the use of shared pointers in JSONParser

Allow access to private header files when defining data members.

Use string_view parameters and call pipeline write methods directly.

Also, make QPDFObjectHandle(std::shared_ptr<QPDFObject> const&) public.