LU-9338 hsm: cache agent record locations

LU-9338 hsm: cache agent record locations

Create a cookie indexed hash of record locations for the agent actions
log. Use this cache to avoid linear scans of the log in HSM RPC
handlers that must update given entries of the log.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I1b9bb0746e88fb0bed81fe1174b5d3c7abac1211
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Faccini Bruno <bruno.faccini@intel.com>
Signed-off-by: Minh Diep <minh.diep@intel.com>
Reviewed-on: https://review.whamcloud.com/26901
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Ben Evans <bevans@cray.com>
Reviewed-by: Quentin Bouget <quentin.bouget@cea.fr>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>