Allow to provide existing EventBridge

[npalm]

Currently the EvenBridge if used is managed by the module. Would be good to allow users to bring in their own EventBridge and allow as well not to use the webhook. This to enable to control their own incoming traffic.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed if no further activity occurs. Thank you for your contributions.