Success case:
- the path endpoint creates and sends a LR_StatusMessage upon
successful path creation
Failure case:
- an intermediate hop creates and sends a LR_StatusMessage upon
failure to forward the path to the next hop for any reason
Both cases:
- transit hops receive LR_StatusMessages and add a frame
to them reflecting their "status" with respect to that path
- the path creator receives LR_StatusMessages and decrypts/parses
the LR_StatusRecord frames from the path hops. If all is good,
the Path does as it would when receiving a PathConfirmMessage.
If not, the Path marks the new path as failed.
LR_StatusMessage is now used/sent in place of PathConfirmMessage
