Deal with CC0091 (static method) and event handling methods

[giggio]

Discussion started on #916.

If we have this in UWP and XAML:

<Button Click="ButtonBase_OnClick" />

And in the code behind:

private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
}

We cannot make this method static, or the event handling will fail. We should not report CC0091 in this scenario.

The way to fix this is alter the analyzer, which already checks method declarations, to ignore them if a signature with two parameters is found, where the first is of type object, and the second is a class that inherits from EventArgs, and the return is void or Task (or a descendant of Task).

[Thieum]

Same goes for Winforms - the code will compile with static methods, but everytime you go in the designer, the lines of designer codes using the static methods will be deleted.