kill any from streaming API Implementation (#14251)

* chore: add JsonValue type

* refactor: kill any from Connection.ts

* refactor: fix StreamEventEmitter contains undefined instead of null

* refactor: kill any from channels

* docs(changelog): Fix: Steaming APIが不正なデータを受けた場合の動作が不安定である問題

* fix license header

* fix lints

packages/backend/src/misc/json-value.ts

@@ -0,0 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+export type JsonValue = JsonArray | JsonObject | string | number | boolean | null;
+export type JsonObject = {[K in string]?: JsonValue};
+export type JsonArray = JsonValue[];