client: get describe_layout by handle/file/link

Signed-off-by: Andras Elso <elso.andras@gmail.com>
libcephfs: fix typos

Signed-off-by: Andras Elso <elso.andras@gmail.com>
libcephfs: get stripe_unit/stripe_count/object_size/pool_id by handle/file/link

Signed-off-by: Andras Elso <elso.andras@gmail.com>
libcephfs: get handle/file/link layout info

Signed-off-by: Andras Elso <elso.andras@gmail.com>
libcephfs: get replication factor of a file handle/file path/link

Signed-off-by: Andras Elso <elso.andras@gmail.com>