Reorganized files and folders

Added IO folder. Moved DirectoryPathBuilder tests there.
Reorganized files and folders #2

Renamed ImageGrabber.Paths to ImageGrabber.IO. Updated usings
accordingly.
Removed FilePathBuilder and related code

It is not needed anymore.
Revert "Removed FilePathBuilder and related code"

This reverts commit 3ab8cfed748c6eaba84e9e6ee83cbd80a520be1f.
Correctly removed FilePathBuilder and related code

It is not needed anymore.