Feature complete catch up with CloudFormation

[cristim]

Functional changes

• Sync forwarded regional events with CloudFormation
• Update module variables, Lambda env vars and IAM policies to match CloudFormation
• Add ManageASG Lambda to support the event-based execution mode

Non-functional changes

• Use Terraform for generating regional code instead of using a Golang script
• Update terraform-null-label to latest version
• Code formatting fixes
• Use native Terraform data objects for IAM policies
• Update Python Lambda runtime to the latest
• Add Terraform example on how to run AutoSpotting
• Maintain upport parallel installations
• Improve logging of the regional event forwarder Lambda

Note: this was only tested to terraform apply successfully, I didn't yet test whether AutoSpotting actually works correctly using it. Testers wanted and any sort of feedback would be really appreciated.