ceph_manager: add object helpers

Add CephManager.methods to get information regarding the pools and PGs
used to store a given object.

Signed-off-by: Loic Dachary <ldachary@redhat.com>
squash ceph_manager: docstring typos
ceph_manager: add ceph_objectstore_tool wrapper

Add the CephManager.objectstore_tool method to encapsulate a call to
ceph_objectstore_tool. The wrapper can convert an object name into the
PG id and figure out the primary OSD. The designated OSD is stopped
before running the command and restarted afterwards.

Signed-off-by: Loic Dachary <ldachary@redhat.com>
repair_test: hinfo_key error injection

Add a function dedicated to erasure coded pools tests, similar to
repair_test_1. Add a corrupter that removes the hinfo_key from the object.

Signed-off-by: Loic Dachary <ldachary@redhat.com>