Changed the lifecycle of the ArchiveRequest to handle the various
combinations of several jobs and their respective success/failures.
Most notably, the request now holds a reportdecided boolan, which
is set when decing to report. This happens when failing to archive
one copy (first failure), or when all copies are transferred (success
for all copies).

Added support for in-mount retries. On falure, the job will be
requeued (with a chance to pick it up again) in the same session
if sane session retries are not exceeded. Otherwise, the job is
left owned by the session, to be picked up by the garbage collector
at tape unmount.

Made disk reporter generic, dealing with both success and failure.
Improved mount policy support fir queueing.

Expanded information avaible in popped element from archive queues.

Added optional parameters to ArchiveRequest::asyncUpdateJobOwner() to
cover various cases.

Updated the archive job statuses.

Clarified naming of functions (transfer/report failure instead of bare
\"failure\").

Updated garbage collector for new archive job statuses.

Added support for report retries and batch reporting in the scheduler
database.

Updated obsolete wording in MigrationReportPacker log messages and error
counts.