Synchronized direct block device I/O & erase support
Synchronized direct block device I/O & erase support

* Open block device with O_SYNC | O_DIRECT to bypass host caches
* Implement a custom scheme to support block erase

Change-Id: I5bd70ae04426d34f4ea8a975f1c06e5c8e47fdb3
GitOrigin-RevId: 219613721786ebab9a85984db015322664732e8b

google-coral/coralmicro-littlefs-fuse,google-coral/coralmicro-littlefs-fuse