Moves conversation.getProps out of models

Co-authored-by: Scott Nonnenberg <scott@signal.org>

ts/util/canAddNewMembers.ts

@@ -0,0 +1,25 @@
+// Copyright 2023 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type { ConversationAttributesType } from '../model-types.d';
+import { SignalService as Proto } from '../protobuf';
+import { isGroupV2 } from './whatTypeOfConversation';
+import { areWeAdmin } from './areWeAdmin';
+
+export function canAddNewMembers(
+  conversationAttrs: ConversationAttributesType
+): boolean {
+  if (!isGroupV2(conversationAttrs)) {
+    return false;
+  }
+
+  if (conversationAttrs.left) {
+    return false;
+  }
+
+  return (
+    areWeAdmin(conversationAttrs) ||
+    conversationAttrs.accessControl?.members ===
+      Proto.AccessControl.AccessRequired.MEMBER
+  );
+}