AWS SAM CLI adds BuildKit support for AWS Lambda functions packaged as container images

[AWS Serverless Application Model Command Line Interface (SAM CLI)](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/using-sam-cli.html) now supports BuildKit for building container images from Dockerfiles, enabling faster, more efficient container image builds for Lambda functions packaged as container images. SAM CLI is a command-line tool for building, testing, debugging, and packaging serverless applications locally before deploying to AWS Cloud. Developers packaging Lambda functions as container images often need advanced build features provided by BuildKit to optimize their images for production. However, SAM CLI previously did not support BuildKit features. Now, with BuildKit support in SAM CLI, you can utilize multi-stage builds to create smaller final images without development dependencies, improved caching to reduce rebuild times, and better parallelization of build steps. BuildKit also enables cross-architecture builds, allowing you to build container images targeting both x86\_64 and arm64 (AWS Graviton2) instruction set architectures from the same development machine. You can also use Docker secrets during builds, keeping sensitive data such as credentials and API keys out of your final image layers. To get started, download or update SAM CLI to version 1.159.0 or later and use the --use-buildkit flag with sam build. This feature works regardless of whether you are using Docker or Finch with SAM CLI, unlocking the full set of BuildKit capabilities. To learn more, visit the [SAM CLI developer guide](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-cli-command-reference-sam-build.html).