Add uninstall stanza for paragon-ntfs

The package did come with an uninstall script, but the script had to take in some sort of folder path as an argument, which I can't seem to determine what it is, so it's pretty much unusable. I did determine the kext/fs files that needed to be deleted, it seems that they don't show up on the result of `./list_loaded_kext_ids` - maybe they would have if I had rebooted? I'm not sure. I used a `:files` directive instead, in case people try to remove it before they reboot and the kext becomes loaded.

Again, the `.pkg` suffix is part of the bundle ID. No launchjobs as far as I can tell.