aws/lambda: Inject deployment configs to Lambda functions

[catsby]

This PR injects the Waypoint deployment env vars into the Lambda function environment, so that the bundled entrypoint has the information it needs to connect to the Waypoint server. This should enable things like config vars to work in lambda functions.

This does expose the values in the functions configuration for all to see, but I don't know if that is a concern or not:

[paladin-devops]

This does expose the values in the functions configuration for all to see, but I don't know if that is a concern or not

If I'm not mistaken, ECS tasks expose the token in a similar way. This AWS blog post recommends using Vault or AWS Secrets Manager. I think integrating with some kind of secrets management solution here, though, doesn't need to be in this PR, and could be a follow-up enhancement.

Also, since it's an invite token (WAYPOINT_CEB_INVITE_TOKEN), I think that means it can be used only once, so after the function redeems the invite token, it shouldn't be able to be used again by an attacker.