Add session token argument to object formatter constructor which is written
to the object. Pass session token from trusted object Put.
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>
