[api/stream] close upstream when socket is disconnected
[api/stream] close upstream when socket is disconnected

resolve #205.

misskey-delta/Misskey-Web,misskey-delta/Misskey-Web,armchair-philosophy/Misskey-Web,armchair-philosophy/Misskey-Web,Tosuke/Misskey-Web,Tosuke/Misskey-Web,Tosuke/Misskey-Web,armchair-philosophy/Misskey-Web,misskey-delta/Misskey-Web,Tosuke/Misskey-Web