First class support for Marten's IChangeListener

[jeremydmiller]

Using this: https://martendb.io/diagnostics.html#listening-for-async-daemon-events

Have a recipe where Marten can designate "side effects" that execute after the projection page is done. Can be either executed inline, or published asynchronously. If being published, make sure the outgoing messages go in the outbox. Flush the outgoing after the page succeeds.