MsalProvider constructor crashes unless you pass scopes

https://github.com/CommunityToolkit/Graph-Controls/blob/d985141a317c96ad571bd9dd8097e38969b649d6/CommunityToolkit.Authentication.Msal/MsalProvider.cs#L63

the default value for scopes is null, but we unconditionally run the `Select(...)` on it. Fix would be to either not provide a default argument for scopes (since it's arguably needed), or at least use `scopes?.Select(...)` so that we don't end up with a null deref.
note there's 2 ctors with this issue