Change separator of file extensions in launching file chooser

 Change separator of file extensions in launching file chooser

 [Title] Change separator of file extensions in launching file chooser
 [Issue#] WEB-1708
 [Problem] File chooser is not work with selected file extensions
 [Cause] separator for multiple file extensions which selected has been changed from Myfiles UG team
 [Solution] change separator from "," to ";" following Myfiles UG usage
 [Team] Browser UI
 [Developer] junghwan kang (junghwan.kang)
 [Request] N/A

Change-Id: I8d94f2ba1fbe2b5df8c3184f0b903ee9a63828df