Add receipt metrics and logs to connected account sync webhooks (#22853)

Webhook deliveries from Google and Microsoft were invisible at the app
level: successful notifications produced no logs and no metrics, so
webhook-triggered syncs could not be told apart from cron polling.

Add two counters, connected-account-sync-webhook/received/messaging and
/received/calendar, mirroring the sync-job metric umbrellas, and log a
line whenever a notification triggers a sync. Unmatched subscriptions
keep their existing warn logs.

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packages/twenty-server/src/engine/core-modules/metrics/types/metrics-keys.type.ts

@@ -53,4 +53,6 @@ export enum MetricsKeys {
   AiChatTurnCompleted = 'ai-chat/turn-completed',
   AiChatTurnFailed = 'ai-chat/turn-failed',
   WorkspaceMetadataCacheLocalEviction = 'workspace-metadata-cache/local-eviction',
+  ConnectedAccountSyncWebhookReceivedMessaging = 'connected-account-sync-webhook/received/messaging',
+  ConnectedAccountSyncWebhookReceivedCalendar = 'connected-account-sync-webhook/received/calendar',
 }