Refactor Event Handling with Explicit Event Streams

[karlem]

Per the comment in the code, we should move away from implicit event serialization. Instead, let's implement an explicit event stream mechanism that batches events during block processing and dispatches them in one go at the end of each block. This change will improve clarity and control over our event handling.

Currently we have a function call (paraphrased) begin and add_tx and end working on memeber Option<X> using take -> modify -> set approach with .except as runtime asserts for correct handling. This is far from perfect and should either be externalized state, an internal envent queue with a tight loop running these operations, or a event stream where the sequence of events can be validated and events be discarded without asserting.

[linear]

IPC-178 Refactor Event Handling with Explicit Event Streams