Allow a on_load_failure_callback to be provided

When entrypoints are loaded it is sometimes useful
to be able to do more than LOG the failure that could
be emitted from the plugin failing to be constructed,
allowing the manager classes to be provided a callback
that can be called when such extension fails to load
is useful to track these types of failures.

Change-Id: Idc7e55ade6b3f80c348123fbceea64425d7d3508
Merge "Allow a on_load_failure_callback to be provided"