Wrap writing events in a lock to avoid race condition

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If multiple threads, or multiple instance of the application attempt to write events to the event store at the same time, it can cause some events to be skipped. For example:

Thread	Action
Writer 1	Starts Transaction
Writer 1	Writes Event and updates the EventStream table with the new ID
Writer 2	Starts Transaction
Writer 2	Writes Event and updates the EventStream table with the new ID (this will be higher than the ID that Writer 1 wrote)
Writer 2	Commits Transaction
Reader	Reads Event committed by Writer 2
Reader	Updates EventSubscription with processed ID
Writer 1	Commits Transaction

The event from Writer 1 will never be processed as its ID is lower than the one that was already processed from Writer 2.

Therefore, we need to ensure that the events are committed in the same order as the IDs are allocated. We cannot perform this locking on the .NET side as there may be multiple instances of the application.