Extend auto-recovery logic

[ferricoxide]

Problem Description:

Auto-recovery logic currently checks the S3 bucket for auto-recovery files but only attempts to use the most-recently written. Extend to attempt to use older backups if more recent ones are corrupt

Fix recommendation:

The auto-recovery function already does a recovery-file validity check as a preflight operation. This logic could be trivially extended to construct and iterate a list of available recovery-files.