WBE notification message validation

Add send and receive validation of the notify
message that is sent between executors and workers
to be more robust around invalid message formats
being sent and received.

Part of blueprint wbe-message-validation

Change-Id: I7300d6f2d00e48c4f989c7f958a028bdff4afdd4
WBE response message validation

Add receive validation of the response message
sent by workers for progress updates and for
result completion to be more robust around invalid
message formats being sent and received.

Part of blueprint wbe-message-validation

Change-Id: I583b9d6344224724d147f2a5b10ddbd23d6a5fdc
Merge "WBE notification message validation"
Merge "WBE response message validation"