Audit culture bugs (#7707)

* Added comments and fixed CultureInfo /  StringComparison where appropriate

* Addressed comments

* Fixed comment

src/modules/launcher/Plugins/Microsoft.Plugin.Calculator/Main.cs

@@ -35,6 +35,7 @@ namespace Microsoft.Plugin.Calculator
 
             try
             {
+                // Using CurrentUICulture since this is user facing
                 var result = CalculateEngine.Interpret(query.Search, CultureInfo.CurrentUICulture);
 
                 // This could happen for some incorrect queries, like pi(2)