PositionalParameterUsed method uses unsafe method to exclude ForEach-Object and Where-Object

[KirkMunro]

Right now the PositionalParameterUsed method in Helper.cs automatically ignores any command that has a parameter set with the name ScriptBlockSet. This is done to ensure that warnings about unnamed positional parameters are not raised for ForEach-Object or Where-Object. This is not a safe way to exclude these cmdlets, because other cmdlets or advanced functions could be created with the same parameter set name (especially if someone uses these as an example to follow). Instead, this should identify the ForEach-Object/Where-Object cmdlets by name.

[yutingc]

This fix has been submitted through #246. Let us know if you have any concerns regarding this rule. Thanks!