SignalR with TypeScript code examples do not match other articles

The method used in the TypeScript example for ChatHub.cs is:
```csharp
public async Task NewMessage(long username, string message)
{
await Clients.All.SendAsync("messageReceived", username, message);
}
```

Both the JavaScript and Blazor examples use:
```csharp
public async Task SendMessage(string user, string message)
{
await Clients.All.SendAsync("ReceiveMessage", user, message);
}
```

The differences being:
- `NewMessage` -> `SendMessage`
- `long username` -> `string user`
- `"messageReceived"` -> `"ReceiveMessage"`

This is also present in the `.ts`/`.js.`|`.razor` examples where they call the methods, and anywhere in the article that references to it of course.
Biggest difference (besides the name changes) is that the TypeScript example doesn't have a username input field, it just uses the `Date().getTime()` value

A smaller but similiar difference is the endpoint defined:

TypeScript example
```csharp
endpoints.MapHub("/hub");
```

versus the JavaScript and Blazor example:
```csharp
endpoints.MapHub("/chathub");
```

This tripped me up personally when I was reading the [Strongly Typed Hubs](https://docs.microsoft.com/en-us/aspnet/core/signalr/hubs?view=aspnetcore-3.1#strongly-typed-hubs) article that uses the JavaScript and Blazor example syntax

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* ID: 47557f89-3a14-1139-0074-38d931b35faf
* Version Independent ID: 1cee43b4-b672-e480-3e26-72e08a6c2d77
* Content: [Use ASP.NET Core SignalR with TypeScript and Webpack](https://docs.microsoft.com/en-us/aspnet/core/tutorials/signalr-typescript-webpack?view=aspnetcore-3.1&tabs=visual-studio&source=docs)
* Content Source: [aspnetcore/tutorials/signalr-typescript-webpack.md](https://github.com/dotnet/AspNetCore.Docs/blob/master/aspnetcore/tutorials/signalr-typescript-webpack.md)
* Product: **aspnet-core**
* Technology: **aspnetcore-tutorials**
* GitHub Login: @ssougnez
* Microsoft Alias: **bradyg**