feat: allow deployment as AWS Lambda

[szubersk]

No description provided.

[jtesta]

Thanks for this PR! Might you be able to make two changes?: 1.) Could you please provide documentation for other users on how to call the function? They would likely appreciate concrete examples for common use cases in the README.md. 2.) Perhaps it would be more clear to rename the function to "aws_lambda_handler". Thanks again!

[jtesta]

After thinking about this more, I have the following question: why would a new lambda_handler() function entry point be necessary, instead of simply running ssh-audit using Python's subprocess module? The advantage to using subprocess is that the existing command-line interface is already well-tested and well-supported.

If this new function only makes things slightly easier for end users, then I'd say its not worth the long-term maintenance cost; it would instead need to make things significantly easier to justify the added cost of maintenance and testing.