Includes:
- fix for unavailable endpoints of client pool,
- session token cache with request retry in case
of missing session token,
- migrated neofs client.
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
Use standard error wrapping/unwrapping instead. The conversion is mostly
straightforward, but see grpc/grpc-go#2934 for GRPC `status.FromError`, it
doesn't currently support unwrapping/errors.As(), so we're unwrapping manually
here.
