Override the default createGenerator(File f, JsonEncoding enc)

When we use writeValue(File file, Object value) to write a CSV, we have got this exception : 
Generator of type com.fasterxml.jackson.core.json.UTF8JsonGenerator does not support schema of type 'CSV'

I found that writeValue(File file, Object value) call the default createGenerator(File f, JsonEncoding enc) that always return an UTF8JsonGenerator. So, I overrode to get a CsvGenerator.

I hope that will also be useful for others.