fix: partial support multi-platform build with automatic platform args

[tky2240]

Summary

This PR fix missing platform arguments (e.g., $TARGETARCH) for multi-platform builds.

Key Changes

• Fixed Argument Substitution: Platform arguments are now resolved within the findBaseImage function based on the CLI execution environment or --platform args.
• Added Base Image Validation: The build will now fail with a error if the base image resolves to a different across the platforms.

How to Test

• ✅ Confirm a multi-platform build succeeds when using a base image with a platform variable (e.g., FROM ${TARGETARCH}-base).
  • src/test/configs/dockerfile-with-automatic-platform-args/
• ❌ Verify that a build fails as expected when using base images that are inconsistent across platforms.
  • src/test/configs/dockerfile-with-inconsistent-base-image/

Related Issus

• https://github.com/microsoft/vscode-remote-release/issues/7582
• https://github.com/microsoft/vscode-remote-release/issues/9605
• https://github.com/devcontainers/cli/issues/275

Note

• This PR is out of scope for Docker Compose.

[tky2240]

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