fastgltf probably shouldn't use tellg to get file sizes, might not always be the file size

[EvilTrev]

Seen here for example:

    std::ifstream file(path, std::ios::ate | std::ios::binary);
    auto length = static_cast<std::streamsize>(file.tellg());
    file.seekg(0);

This has some issues, and there is a bunch of discussion here: https://stackoverflow.com/questions/2409504/using-c-filestreams-fstream-how-can-you-determine-the-size-of-a-file

But long, short, if using c++17 or later, then:

   auto length = std::filesystem::file_size( path );

[spnda]

I am aware of this issue and I do use this answer's idea in the GltfDataBuffer. Could you please pinpoint a line where I do use tellg? (I tried looking for tellg in the code on my phone but it doesn't seem to catch the occurences)

Also, is the filesystem method any more exact than what I currently use?