[Bug] [WAM] Using WAM when a console app is started as an exe results in exception because of null sync context

[pmaytak]

Which version of MSAL are you using?
Latest 4.30.1

Platform
NetFx/Net5 console app using WAM

Repro

1. Build NetFxConsoleApp.
2. Run the app executable directly (not from Visual Studio).

Expected behavior
WAM account picker control is shown.

Actual behavior
An exception is thrown because the sync context is null here:

microsoft-authentication-library-for-dotnet/src/client/Microsoft.Identity.Client/Platforms/Features/WamBroker/AccountPicker.cs

Lines 80 to 86 in 36c1113

	{
	throw new MsalClientException(
	MsalError.WamUiThread,
	"AcquireTokenInteractive with broker must be called from the UI thread when using the Windows broker." +
	WamBroker.ErrorMessageSuffix);
	}

Possible solution
Add a check if _synchronizationContext is null in UseSplashScreen().

[pmaytak]

This is included in MSAL 4.31.0 release.