add an option for file order

[npes87184]

Hi, @Angads25

Add option let user select which order they prefer.

It provide four types now. The following is the list of types.

• FILE_ORDER_NAME_ASCENDING
• FILE_ORDER_NAME_DESCENDING
• FILE_ORDER_DATE_ASCENDING
• FILE_ORDER_DATE_DESCENDING

I think it is a basic function that a filepicker lib should provide. I hope you can merge it, if you have any problems or concerns, feel free to say.

btw, I have fixed some typos in comment.

Thanks.