"Add await" should be upgraded to a codefix in presence of CS4014

[DoctorKrolic]

Currently roslyn provides "Add await" refactoring for cases like this:

async Task<int> GetNumberAsync()
{
    var x = GetNumberAsync()[||];
    return 0;
}

However the same refactoring is provided in cases when compiler raises CS4014 warning about not awaiting a task-returing method inside another async method:

async void M()
{
    [|DoSomethingAsync()|]; // CS4014 here
}

Task DoSomethingAsync() => Task.CompletedTask;

Problems here are:

• The fix for the diagnostic is not on top of the action list:
  
• There is no fix-all. And even if we can add fix-all to refactorings, I want to fix only warning cases, not every place where await can be added

Therefore I think "Add await" should be split into refatoring and a codefix part - it should appear as a codefix with propper fix-all support for cases of CS4014 and just a refactoring in other valid places