feat: suspend instance improvements (#13861)

* feat(backend): dead instance detection

* feat(backend): suspend type detection

* feat(frontend): show suspend reason on frontend

* feat(backend): resume federation automatically if the server is automatically suspended

* docs(changelog): 配信停止まわりの改善

* lint: fix lint errors

* Update packages/frontend/src/pages/instance-info.vue

* lint: fix lint error

* chore: suspendedState => suspensionState

---------

Co-authored-by: syuilo <4439005+syuilo@users.noreply.github.com>

packages/backend/migration/1716345015347-NotRespondingSince.js

@@ -0,0 +1,16 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+export class NotRespondingSince1716345015347 {
+    name = 'NotRespondingSince1716345015347'
+
+    async up(queryRunner) {
+        await queryRunner.query(`ALTER TABLE "instance" ADD "notRespondingSince" TIMESTAMP WITH TIME ZONE`);
+    }
+
+    async down(queryRunner) {
+        await queryRunner.query(`ALTER TABLE "instance" DROP COLUMN "notRespondingSince"`);
+    }
+}