Update tegola_lambda to align with AWS Go runtime deprecation and migration to al2

[ARolek]

AWS has announced they're deprecating the Go runtime from lambda, but Go functions can still be run on lambda using the provided.al2 runtime. This change is slated to happen December 31, 2023 and aligns with them sunsetting Amazon Linux 1.

AWS has provided a guide to help with the migration. Upon the first read it looks rather simple but I still need to step through it end to end. The following changes will need to be made to tegola to support this change:

• Change the name of the binary output by go build to bootstrap.
• Update the tegola_lambda CI to output amd and arm builds. This will allow for users to take advantage of Graviton 2 instances.
• Update the associated READMEs

Since this change is coming to AWS fairly quickly, there's no need to support backwards compatibility on the previous approach to deploying tegola_lambda.