add encoding as "UTF-8-BOM" in the file translator override property

it will be good if teiid supports Encoding to "UTF-8-BOM" since other middleware technologies supports similar to this and also even editor such as Notepad++ supports to convert / save file as "UTF-8-BOM".

Currently we have added Translator override for File to include "Encoding Property to UTF-8" so similarly we should be able to set it to "UTF-8-BOM" , instead of writing code manually to add BOM to generate a file.