Add "File Filter" method to Windows similar to the "install_service" method

This is as a result of the work needed for PA-768, where the file puppetres.dll needs to be filtered from from the Heat/Harvest process for special treatment.

The "filter_file" method should add an entry to the filter.xslt file similar to that done for the service entries so that the selected file is excluded from the heat/harvest wix operation.

Once this is completed, the Puppet Agent specific instance of filter.xslt.erb should be deleted.