LargeFileId is the same wire-level shape as FileId but is a
distinct brand so that "ID of an in-progress multipart upload" and
"ID of a committed file version" don't get mixed up by accident.
b2_start_large_file returns one; b2_finish_large_file consumes it
and produces a regular FileId.
Creates a branded LargeFileId from a raw string.
LargeFileIdis the same wire-level shape asFileIdbut is a distinct brand so that "ID of an in-progress multipart upload" and "ID of a committed file version" don't get mixed up by accident.b2_start_large_filereturns one;b2_finish_large_fileconsumes it and produces a regularFileId.