make the event bus optional

[DavidBadura]

The event bus is no longer required to react to events in the form of a processor or projector. We now have the option to handle everything with the subscription engine. That's why the event bus should no longer be required, but optional.

[github-actions]

Hello 👋

here is the most recent benchmark result:

SubscriptionEngineBench
=======================

+---------------------------+-----------------+-----------------+-----------------+------------+
|                           | time (kde mode)                   | memory                       |
+---------------------------+-----------------+-----------------+-----------------+------------+
| subject                   | Tag: <current>  | Tag: base       | Tag: <current>  | Tag: base  |
+---------------------------+-----------------+-----------------+-----------------+------------+
| benchHandle10000Events () | 3.217s (±0.00%) | 3.265s (±0.00%) | 39.094mb        | 39.098mb   |
+---------------------------+-----------------+-----------------+-----------------+------------+

SplitStreamBench
================

+-------------------------+--------------------+--------------------+-----------------+------------+
|                         | time (kde mode)                         | memory                       |
+-------------------------+--------------------+--------------------+-----------------+------------+
| subject                 | Tag: <current>     | Tag: base          | Tag: <current>  | Tag: base  |
+-------------------------+--------------------+--------------------+-----------------+------------+
| benchLoad10000Events () | 5.402ms (±0.00%)   | 5.440ms (±0.00%)   | 42.563mb        | 42.564mb   |
| benchSave10000Events () | 525.491ms (±0.00%) | 619.436ms (±0.00%) | 42.574mb        | 42.841mb   |
+-------------------------+--------------------+--------------------+-----------------+------------+

SimpleSetupBench
================

+----------------------------------------+--------------------+--------------------+-----------------+------------+
|                                        | time (kde mode)                         | memory                       |
+----------------------------------------+--------------------+--------------------+-----------------+------------+
| subject                                | Tag: <current>     | Tag: base          | Tag: <current>  | Tag: base  |
+----------------------------------------+--------------------+--------------------+-----------------+------------+
| benchLoad10000Events ()                | 161.105ms (±0.00%) | 161.830ms (±0.00%) | 38.698mb        | 38.699mb   |
| benchSave1Event ()                     | 929.900μs (±0.00%) | 866.300μs (±0.00%) | 38.698mb        | 38.699mb   |
| benchSave10000Events ()                | 381.391ms (±0.00%) | 455.351ms (±0.00%) | 38.698mb        | 38.965mb   |
| benchSave10000Aggregates ()            | 9.246s (±0.00%)    | 9.177s (±0.00%)    | 38.698mb        | 38.699mb   |
| benchSave10000AggregatesTransaction () | 7.319s (±0.00%)    | 7.334s (±0.00%)    | 38.698mb        | 38.699mb   |
+----------------------------------------+--------------------+--------------------+-----------------+------------+

SnapshotsBench
==============

+----------------------------------------+--------------------+--------------------+-----------------+------------+
|                                        | time (kde mode)                         | memory                       |
+----------------------------------------+--------------------+--------------------+-----------------+------------+
| subject                                | Tag: <current>     | Tag: base          | Tag: <current>  | Tag: base  |
+----------------------------------------+--------------------+--------------------+-----------------+------------+
| benchLoad10000EventsMissingSnapshot () | 162.696ms (±0.00%) | 157.509ms (±0.00%) | 38.695mb        | 38.696mb   |
| benchLoad10000Events ()                | 503.900μs (±0.00%) | 505.300μs (±0.00%) | 38.695mb        | 38.696mb   |
+----------------------------------------+--------------------+--------------------+-----------------+------------+

This comment gets update everytime a new commit comes in!