Implement fastfat overflow queue

This lets CrystalDiskMark finish, i.e. fixes the issue described in the comment in CORE-17328:

It did prevent the BSOD for me reliably also on 0.4.14-RC, which I do consider a progress definitely. But afterwards I had a hanging DiskSpd32L.exe in taskmgr, that was impossible to kill and any write operations to the disk were rejected / seemingly hanging in the OS, even after 15minutes and more. Whenever any process tried to write anything I got the pending

(ntoskrnl/cc/copy.c:789) Actively deferring write for ...

Finally I got

(ntoskrnl/io/iomgr/irp.c:1200) Broken driver did not complete!