Reduce boiler plate code for getting the current user in a Blazor component

In a Blazor component if you want to get the current user you typically have to do something like this:

```csharp
protected override async Task OnInitializedAsync()
{
var authenticationState = await AuthenticationStateTask;
CurrentUser = authenticationState.User;
}

[CascadingParameter]
public Task AuthenticationStateTask { get; set; } = default!;

public ClaimsPrincipal CurrentUser { get; set; } = default!
```

There are several things going on here: a special cascading parameter, overriding a component lifecycle event, and async logic to get the auth state. It's quite a bit more complicated than the convenient `User` property we have in MVC & Razor Pages. And you need this code wherever you want access to the current user. Is there something we could do to cut down on the amount of boiler plate code to get the current user?