feat: Add UIImageFileManager (issues #4)

[minjae9610]

Solve Issue #4

• Use singleton pattern

• Usage

  • UIImageFileManager.shared.[function name]

• saveImage(image: UIImage, path: String = "", fileName: String)

  • Create directory if path directories are not exist
  • Save image as fileName in path directory
  • Return true if success to save file
  • Return false if fail to save file

• getSavedImage(path: String = "", fileName: String)

  • Load fileName image in path directory
  • Return UIImage if fileName image file exist in path directory
  • Return Nil if can not find fileName file in path directory

• deleteSavedImage(path: String = "", fileName: String)

  • Delete fileName file in path directory
  • Return true if success to delete file
  • Return false if fail to delete file