Moves parts of conversation view into redux

ts/util/startConversation.ts

@@ -0,0 +1,19 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type { UUIDStringType } from '../types/UUID';
+import { strictAssert } from './assert';
+
+export function startConversation(e164: string, uuid: UUIDStringType): void {
+  const conversation = window.ConversationController.lookupOrCreate({
+    e164,
+    uuid,
+    reason: 'util/startConversation',
+  });
+  strictAssert(
+    conversation,
+    `startConversation failed given ${e164}/${uuid} combination`
+  );
+
+  window.Whisper.events.trigger('showConversation', conversation.id);
+}