Nil slice of records of the `Table` should be converted to nil slice in
corresponding field of API v2 message structure.
Add nil-check in `Table.ToV2` implementation. The changes fix corresponding
unit test.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Document field values of instance constructed via `NewTable`. Assert the
values in corresponding unit test.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Extended ACL table can be set within a session, and should be signed.
Add `SessionToken` / `SetSessionToken` (`Signature` / `SetSignature`)
methods to carry session token (signature) in `Table` structure.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
