Add label to rageshakes for React soft crashes

This adds a label all rageshakes submitted via the React error boundary marking
them as soft crashes for triage.

Fixes https://github.com/vector-im/riot-web/issues/11072

src/rageshake/submit-rageshake.js

@@ -1,6 +1,7 @@
 /*
 Copyright 2017 OpenMarket Ltd
 Copyright 2018 New Vector Ltd
+Copyright 2019 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.
@@ -81,6 +82,10 @@ export default async function sendBugReport(bugReportEndpoint, opts) {
         body.append('device_id', client.deviceId);
     }
 
+    if (opts.label) {
+        body.append('label', opts.label);
+    }
+
     if (opts.sendLogs) {
         progressCallback(_t("Collecting logs"));
         const logs = await rageshake.getLogsForReport();