Audit culture bugs (#7707)

* Added comments and fixed CultureInfo /  StringComparison where appropriate

* Addressed comments

* Fixed comment

src/modules/imageresizer/tests/Views/TimeRemainingConverterTests.cs

@@ -28,6 +28,7 @@ namespace ImageResizer.Views
             var timeRemaining = new TimeSpan(hours, minutes, seconds);
             var converter = new TimeRemainingConverter();
 
+            // Using InvariantCulture since these are internal
             var result = converter.Convert(
                 timeRemaining,
                 targetType: null,