Couldn't support DnsEndPoint to configure the servers with options.UseSslStream=false

[IvanDeng]

Suggest to update MemcachedClientConfiguration.ConfigureServers like below, if the configured address is not a valid IPAddress, then treat it as a dns endpoint. Or you can add a option like IsDnsAddress in MemcachedClientOptions.cs to make it configurable while register the service by AddEnyimMemcached.

private void ConfigureServers(MemcachedClientOptions options)
{
Servers = new List();
foreach (var server in options.Servers)
{
if (options.UseSslStream)
{
AddServer(server.Address, server.Port);
}
else
{
_logger.LogInformation($"Memcached server address - {server.Address}:{server.Port}");
if (!IPAddress.TryParse(server.Address, out var address))
{
Servers.Add(new DnsEndPoint(server.Address, server.Port));
}
else
{
Servers.Add(new IPEndPoint(address, server.Port));
}

    }
}

}