Run AWS handler for Elastic Serverless Forwarder locally

[aspacca]

Describe the enhancement:

Provide a way to run the lambda handler locally accepting different kind of trigger events.
Ideally we will be able to run the handler from an IDE with a debugger attached.

Describe a specific use case for the enhancement or feature:

Currently you need to deploy a new version of the lambda in SAR on a development account and test a payload through AWS console. Or wrap your own __main__ entry-point that's not versioned if you want to run locally/with debugger.

This is far from ideal and providing this feature will improve developers experience.

[endorama]

We are not going to work on this item in the near future, but we plan to add guidance on how to do run the handler separately in the CONTRIBUTING.md file as an improvement.

We welcome contributions on this issue!