add webhook id to test webhook (#7884)

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## PR-Codex overview
This PR introduces a new optional property `webhook_id` to the `TestWebhookPayload` interface and updates the call to `testWebhook` to include this new property.

### Detailed summary
- Added an optional property `webhook_id` to the `TestWebhookPayload` interface in `webhooks.ts`.
- Updated the `testWebhook` function call in `useTestWebhook.ts` to include `webhook_id` when invoking the function.

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<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

* **Bug Fixes**
  * Test Webhook requests now include the specific webhook ID when available, ensuring the test targets the correct webhook and improving reliability.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: nischitpra

apps/dashboard/src/@/api/insight/webhooks.ts

@@ -58,6 +58,7 @@ interface WebhookSingleResponse {
 }
 
 interface TestWebhookPayload {
+  webhook_id?: string;
   webhook_url: string;
   type?: "event" | "transaction";
 }

apps/dashboard/src/app/(app)/team/[team_slug]/[project_slug]/(sidebar)/webhooks/hooks/useTestWebhook.ts

@@ -41,7 +41,7 @@ export function useTestWebhook(clientId: string) {
       });
 
       const result = await testWebhook(
-        { type, webhook_url: webhookUrl },
+        { type, webhook_url: webhookUrl, webhook_id: id },
         clientId,
       );