Add a sample on WebAuthenticationCoreManager::CreateWebAccountMonitor Method

[wdxg]

Which sample are you requesting a feature to be added to?

A sample using Cpp/WinRT WebAuthenticationCoreManager::CreateWebAccountMonitor Method.

For example:

1. get all accounts to keep an account list
2. monitor each account and update the list if needed
3. does it need to update the monitor list if an account has been deleted?
4. how to use "DefaultSignInAccountChanged" event?

Describe the feature
Developer don't know exactly how to use WebAuthenticationCoreManager::CreateWebAccountMonitor Method even with the official doc. That is too simple. This method takes an account list, what needs to be done if some account in the list has been deleted?