pytsk/libtsk does not correctly/fully handle FAT-12, FAT16, FAT-32

[joachimmetz]

• https://github.com/sleuthkit/sleuthkit/issues/2527
• https://github.com/sleuthkit/sleuthkit/issues/2528
• https://github.com/sleuthkit/sleuthkit/issues/2715
• https://github.com/sleuthkit/sleuthkit/issues/2629