Commit a1b53c660e introduced a regression which caused images that
were shown for sending confirmation as a file path + image not being
passed to FileLoadTask in _image field, they were passed in the
_information field instead. They were not sent in case the file path
was not existing at the moment of processing. If the file path does
not exist anymore read the image from _information and send it.
Server has some extensions checking for inputMediaUploadedPhoto,
so force the extension to be .jpg anyway. It doesn't matter,
because the filename from inputFile is not used anywhere.
Also own PhotoData::UploadingData through std::unique_ptr.
Read media information (image / song / video) in SendFileBox in the
same way it is read in FileLoadTask::process() and reuse it in
FileLoadTask if it was loaded already for the box.
