Add function for filename handling

[viper4gh]

Filenames are needed in several cases:

• save recording
• drivertable single export and race weekend export
• tracktable export
• autoexport drivertable

[viper4gh]

ToDo:

• check if AutoExport is working
• remove file extension handling from function and add it after the function call, because the CSV export is adding it or
• leave file extension in the function and remove it in the ExportCSV function

[viper4gh]

Implementation completed