Add ESF lambda ARN to SAR output

[vfeinman]

Describe the enhancement:
Bubble up the ESF lambda ARN through stack/application output so that any ESF lambda dependent resources can be created based on the lambda ARN generated by the application.

Describe a specific use case for the enhancement or feature:
On a number of occasions the ESF lambda concurrent executions spiked, consuming the account limit for Lambda concurrent executions. This has the undesirable effect of preventing production applications from running and extremely high costs. We currently have to deploy the ESF Serverless Application Repository application, then manually set the reserved concurrent executions manually. I'd also like the ability to have native AWS CloudWatch monitoring the ESF lambda, which I'm not able to do in a scalable way since I don't have any access to lambda ARN created through the ESF application.