Detect calling GetService on background thread

[flcdrg]

Avoid the following error:

SetSite failed for package [VSPackage]Source: 'Microsoft.VisualStudio.Shell.14.0' Description: Due to high risk of deadlock you cannot call GetService from a background thread in an AsyncPackage derived class. You should instead call GetServiceAsync (without calling Result or Wait on the resultant Task object) or switch to the UI thread with the JoinableTaskFactory.SwitchToMainThreadAsync method before calling GetService. System.InvalidOperationException: Due to high risk of deadlock you cannot call GetService from a background thread in an AsyncPackage derived class. You should instead call GetServiceAsync (without calling Result or Wait on the resultant Task object) or switch to the UI thread with the JoinableTaskFactory.SwitchToMainThreadAsync method before calling GetService.

at Microsoft.VisualStudio.Shell.AsyncPackage.GetService(Type serviceType)
at Microsoft.VisualStudio.Shell.Package.System.IServiceProvider.GetService(Type serviceType)
at RLExtension.AddTestsItem..ctor(Package package) in C:\buildAgent\work\30592ae9f88624c9\RLExtension\AddTestsItem.cs:line 31
at RLExtension.VSPackage.d__2.MoveNext() in C:\buildAgent\work\30592ae9f88624c9\RLExtension\VSPackage.cs:line 69
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Microsoft.VisualStudio.Shell.AsyncPackage.<>c__DisplayClass16_0.<b__1>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at Microsoft.VisualStudio.Services.VsTask.RethrowException(AggregateException e)
at Microsoft.VisualStudio.Services.VsTask.InternalGetResult(Boolean ignoreUIThreadCheck)
at Microsoft.VisualStudio.Services.VsTask.GetResult()