Added option to TagOptionSingleton to disable Files.isWritable check

This change disables the use of the Files.isWritable API when opening or making changes to files.

Files.isWritable was found by me to be unreliable; giving false negatives under certain conditions. For example, when a file is accessed using Samba, and the Samba server uses force-user to allow a guest to modify a file, I found Files.isWritable returned false, despite Windows allowing edits of the file from the same location.