Abstract electron settings properly to avoid boilerplate-hell (#8798)

* Remove unused method `BasePlatform::screenCaptureErrorString`

* Improve platform typescripting

* Remove redundant awaits

* Abstract electron settings properly to avoid boilerplate-hell

* i18n

* Fix stray semi-colons

* Fix setting level order for Platform settings

src/settings/handlers/PlatformSettingsHandler.ts

@@ -0,0 +1,40 @@
+/*
+Copyright 2022 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 SettingsHandler from "./SettingsHandler";
+import PlatformPeg from "../../PlatformPeg";
+
+/**
+ * Gets and sets settings at the "platform" level for the current device.
+ * This handler does not make use of the roomId parameter.
+ */
+export default class PlatformSettingsHandler extends SettingsHandler {
+    public canSetValue(settingName: string, roomId: string): boolean {
+        return PlatformPeg.get().supportsSetting(settingName);
+    }
+
+    public getValue(settingName: string, roomId: string): any {
+        return PlatformPeg.get().getSettingValue(settingName);
+    }
+
+    public setValue(settingName: string, roomId: string, newValue: any): Promise<void> {
+        return PlatformPeg.get().setSettingValue(settingName, newValue);
+    }
+
+    public isSupported(): boolean {
+        return PlatformPeg.get().supportsSetting();
+    }
+}