phosphor-ipmi-flash state recovery

[Patrick Voelker]

> > Internally, it looks like I need to get to abortProcess() but to do that I need
> to close the current session but I don’t have a way to obtain the sessionID
> after the fact.  Also the stale session doesn’t seem to expire (as mentioned
> in the readme.md) and I can’t find the support for that in the code.
> 
> https://github.com/openbmc/phosphor-ipmi-
> flash/blob/master/bmc/firmware_handler.cpp#L95
> 
> You should be able to just delete any of the blob Id paths, such as
> the active blob path, and that should trigger what you want.

As coded, that only works to abort when in in the verificationPending and updatePending states.  That won't work if it's stuck in the middle of an aborted transfer with a session that's still open.