[Host.Outbox] optimistic mode - hybrid strategy

[dundich]

Is it often the case that the bus is unavailable?
if the sequence of messages is not of particular interest. Maybe we should provide for writing to the outbox only when the bus is unavailable (exception) - and add an option with a hybrid strategy?

ps. hybrid strategy - just a “save -> don't save” checkbox in the outbox if the bus is unavailable

Originally posted by @dundich in #313

[dundich]

Interception points

1. current (classic) mode (PRE): first outbox -> transport (https://microservices.io/patterns/data/transactional-outbox.html)
2. or optimistic mode (POST): first transport -> if error -> outbox ([Host.Outbox] optimistic mode - hybrid strategy #316)
3. CircuitBreaker (CRON?) : if no healthcheck-> outbox -> transport #251 Health check circuit breaker #282