[STU-148] [FR] Use Field name instead of handle in column header

[HannahDeWachter]

Is it possible to use the Field's name instead of the handle?
Another nice feature would be if you can choose the value shown in the header (add a text input field for each field to choose the value of the column header)

_STU-148

[janhenckens]

Check if field names are included here https://github.com/studioespresso/craft-exporter/blob/develop/src/elements/ExportElement.php#L311