java: support stat()

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
java: support fchmod

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
java: add missing chmod unmounted test

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
java: fix exception name typo

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
libcephfs: document ERANGE rv for get_file_pool_name

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
java: support ceph_get_file_pool_name

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>