tools: Cleanups in ceph_filestore_dump

Fix usage output of ceph_filestore_dump
Add missing error checking
Output full object name
Improve message consistency
Fix program exit value

Signed-off-by: David Zafman <david.zafman@inktank.com>
tools: Fix ceph_filestore_dump to fully operate on EC pools

Add spg_t and ghobject_t handling

Fixes: #7698

Signed-off-by: David Zafman <david.zafman@inktank.com>
test: Add ceph_filestore_dump.sh to test ceph_filestore_dump

Signed-off-by: David Zafman <david.zafman@inktank.com>
Merge pull request #1463 from ceph/wip-7698

Reviewed-by: Samuel Just <sam.just@inktank.com>