Warn when demoting self via /op and /deop slash commands (#11214)

* Warn when demoting self via /op and /deop slash commands

* Iterate and DRY

* i18n

* Improve coverage

* Improve coverage

* Improve coverage

* Iterate

src/slash-commands/interface.ts

@@ -0,0 +1,34 @@
+/*
+Copyright 2015, 2016 OpenMarket Ltd
+Copyright 2018 New Vector Ltd
+Copyright 2019 Michael Telatynski <7t3chguy@gmail.com>
+Copyright 2020, 2023 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { IContent } from "matrix-js-sdk/src/matrix";
+
+import { _td } from "../languageHandler";
+import { XOR } from "../@types/common";
+
+export const CommandCategories = {
+    messages: _td("Messages"),
+    actions: _td("Actions"),
+    admin: _td("Admin"),
+    advanced: _td("Advanced"),
+    effects: _td("Effects"),
+    other: _td("Other"),
+};
+
+export type RunResult = XOR<{ error: Error }, { promise: Promise<IContent | undefined> }>;