feat(function): add Docker build options for Python container functions

[danielivanovz]

Summary

Adds support for Docker build options (buildArgs, secrets, target, network, ssh) when deploying Python functions as container images. These options are passed through to the @pulumi/docker-build Image component.

Motivation

When deploying Python Lambda functions as containers, users often need to:

• Pass build-time arguments (e.g., version info, feature flags)
• Use secrets for private package registries like AWS CodeArtifact
• Target specific stages in multi-stage Dockerfiles
• Configure network mode for build-time dependencies
• Forward SSH keys for private Git repositories

Changes

• Extended the python interface in FunctionArgs with new optional properties
• Updated createImageAsset() to pass these options to the Docker Image component
• Added example and documentation in examples/aws-python-container/

Example Usage

new sst.aws.Function("MyFunction", {
  python: {
    container: true,
    buildArgs: { GIT_COMMIT: "abc123" },
    secrets: { CODEARTIFACT_AUTH_TOKEN: process.env.CODEARTIFACT_AUTH_TOKEN },
    target: "production",
  },
  handler: "src/api.handler",
  runtime: "python3.11",
});