In previous implementation parent object header finalized twice in size
limiter + formatter. On the one hand, this added redundant action, on the
other hand, it could provoke a difference in the headers of the linking and
the last part. Change formatter to finalize parent header if it does not
container the signature. Change size limiter to reuse parent header after
last child finalization in linking child.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Define object writer interface. Implement payload size limiter that
restricts payload size of the object. Implement object format moulder that
fill verification fields and finalizes object structure.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
