feat: Add configurable single event delivery for ServiceBus subscribers

[Copilot]

Azure EventGrid to ServiceBus delivers events as single JSON objects, not arrays. The simulator always wrapped events in arrays, requiring workarounds in event parsing logic.

Changes

• IEventSchemaFormatter: Added SerializeSingle() method to serialize events without array wrapper
• Formatters: Implemented SerializeSingle() in CloudEventSchemaFormatter and EventGridSchemaFormatter
• ServiceBusSubscriberSettings: Added singleEventDelivery boolean property
• ServiceBusEventDeliveryService: Uses SerializeSingle() when singleEventDelivery == true

Usage

{
  "serviceBus": [{
    "name": "MySubscriber",
    "queue": "my-queue",
    "singleEventDelivery": true
  }]
}

Configuration	Output	Notes
true	{...}	Matches Azure behavior
false or omitted	[{...}]	Backward compatible (default)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Feature]: EventGrid to ServiceBus as SingleEvent</issue_title>
<issue_description>### Problem Statement

When EventGrid sends to ServiceBus in Azure, the actual messages on the ServiceBus topic are not arrays with a single item.

In the CloudEventSchemaFormatter, it is hard-coded as sending through as an array of a single item:
https://github.com/pm7y/AzureEventGridSimulator/blob/master/src/AzureEventGridSimulator/Domain/Services/CloudEventSchemaFormatter.cs#L33
So, has an array wrapper in the serialized ServiceBusReceivedMessage.Body.

It would be great if this was configurable to simulate what actually happens in Azure. We've had to add extra logic to check for arrays in our event parser to handle this, which I'd prefer to not be needed.

This is a great project otherwise and really helpful to not have to point to Azure locally.

Proposed Solution

Configuration read in the ServiceBusEventDeliveryService that can be passed to the CloudEventSchemaFormatter or EventGridSchemaFormatter to return as SingleEvent:
https://github.com/pm7y/AzureEventGridSimulator/blob/master/src/AzureEventGridSimulator/Domain/Services/Delivery/ServiceBusEventDeliveryService.cs#L62C17-L62C22

Or change that to the default logic, since that is how EventGrid to ServiceBus message delivery works in Azure.

Alternatives Considered

No response

Feature Category

Configuration

Use Case

EventGrid to ServiceBus topic using CloudEvent schema.

Contribution

• I would be willing to submit a PR for this feature</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Feature]: EventGrid to ServiceBus as SingleEvent #259

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.