[#62] client: move package from neofs-api-go

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

client/raw.go

@@ -0,0 +1,17 @@
+package client
+
+import (
+	"io"
+
+	"github.com/nspcc-dev/neofs-api-go/rpc/client"
+)
+
+// Raw returns underlying raw protobuf client.
+func (c *clientImpl) Raw() *client.Client {
+	return c.raw
+}
+
+// implements Client.Conn method.
+func (c *clientImpl) Conn() io.Closer {
+	return c.raw.Conn()
+}