addThreadMember method
Add a member to a thread.
Implementation
Future<void> addThreadMember(Snowflake id, Snowflake memberId) async {
final route = HttpRoute()
..channels(id: id.toString())
..threadMembers(id: memberId.toString());
final request = BasicRequest(route, method: 'PUT');
await client.httpHandler.executeSafe(request);
}