Define base `Status` interface. Provide the functionality to distinguish
success and failure returns. Provide functionality to transport statuses
over NeoFS API V2 protocol. Support success `OK` and failure `INTERNAL`
returns.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Another possible panic (though quite rare).
```
--- FAIL: TestTwoNodes (0.00s)
pool.go:185: Unexpected call to *pool.MockClient.EndpointInfo([context.Background.WithCancel.WithDeadline(2021-10-26 15:50:50.005585875 +0300 MSK m=+1.216577808 [-940.323µs])]) at /home/dzeta/repo/neofs-sdk-go/pool/pool.go:185 because: there are no expected calls of the method "EndpointInfo" for that receiver
pool.go:185: Unexpected call to *pool.MockClient.EndpointInfo([context.Background.WithCancel.WithDeadline(2021-10-26 15:50:50.005715623 +0300 MSK m=+1.216707547 [-1.351991ms])]) at /home/dzeta/repo/neofs-sdk-go/pool/pool.go:185 because: there are no expected calls of the method "EndpointInfo" for that receiver
```
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
We have go1.16 in go.mod and `gomock.NewController` comment indicates:
```
New in go1.14+, if you are passing a *testing.T into this function you no
longer need to call ctrl.Finish() in your test methods.
```
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
Since we transformed the pool of gRPC connection into the pool of
neofs clients, we don't need to call EndpointInfo to fetch the
address of the node for the beautiful error output.
Moreover it is done incorrectly, because c.CreateSession may return
context.Cancelled error (graceful shutdown). We will reuse the same
context for the EndpointInfo call which will lead to a
timeout freeze.
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
