Core changes:
* avoid package-colliding variable naming
* avoid using pointers to IDs where unnecessary
* avoid using `idSDK` import alias pattern
* use `EncodeToString` for protocol string calculation and `String` for
printing
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Move in-memory session storage to the separate directory of `storage`. It is
done for future support of different kind of session storages.
Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
Return `SessionTokenExpired`/`SessionTokenNotFound` error from
`apistatus` package if private session token is expired/missing. These
errors are returned by storage node's server as NeoFS API statuses.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
