"Web API calls MS Graph" add example called via web application/client based like Blazor or MVC .NET 6

### This issue is for a: (mark with an `x`)
```
- [ ] bug report -> please search issues before submitting
- [ ] feature request
- [x] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)
```

### Minimal steps to reproduce
I tried to use the example *Web API now calls Microsoft Graph* example, but now it will be called via a web application like MVC or Blazor in .NET 6. As soon as the WebApi calls the MSGraph via the WebApp, a MsalUiRequiredException is thrown.
The InnerException is of type MicrosoftIdentityWebChallengeUserException. I would like to see an example which follows the OBO flow but then called via a .NET 6 web application. Thus via WebApp -> WebApi -> MS Graph.

The WebApi replies now with following code during handling the exception:
_tokenAcquisition.ReplyForbiddenWithWwwAuthenticateHeader(_graphOptions.Value.Scopes.Split(' '), challengeException.MsalUiRequiredException);

How can I handle MsalUiRequiredException or Forbidden response in the web application passed by the web API?

I think my configuration in Azure AD is correct, as the native client (XAML) application works.

Can you give me some pointers, to solve my problem?

### Any log messages given by the failure
The following exception message is shown in the debugger for the WebApi: IDW10502: An MsalUiRequiredException was thrown due to a challenge for the user. See https://aka.ms/ms-id-web/ca_incremental-consent.

### Expected/desired behavior
Use this example with the On-Behalf-Of flow as well called via a web application like MVC and/or Blazor created in .NET 6.

### OS and Version?
Windows 10

### Versions
Windows 10 20H2; .NET 6 (6.0.2); Microsoft.Identity.Web 1.23.0

### Mention any other details that might be useful
I know there is an example active-directory-aspnetcore-webapp-openidconnect-v2/4-WebApp-your-API, but the WebAPI doesn't call MS Graph.