* fix(eventstore): prevent allocation of filtered events
Directly reduce each event obtained from a sql.Rows scan,
so that we do not have to allocate all events in a slice.
* reinstate the mutex as RWMutex
* scan data directly
* add todos
* fix(writemodels): add reduce of parent
* test: remove comment
* update comments
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Co-authored-by: adlerhurst <silvan.reusser@gmail.com>