buildsys: add feature to vendor go modules

[samuelkarp]

Issue number: https://github.com/bottlerocket-os/bottlerocket/issues/2052

Description of changes: This pull request implements Option C in https://github.com/bottlerocket-os/bottlerocket/issues/2052: changes to buildsys that enable automatic Go module downloads ahead of the rpmbuild invocation.

Testing done:

cargo make -e PACKAGE=oci-add-hooks build-package
cargo make -e PACKAGE=hotdog build-package

cargo make -e BUILDSYS_VARIANT=aws-ecs-1

Launch an aws-ecs-1 AMI, verify that oci-add-hooks are built properly and have dependency licenses in /usr/share/licenses

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.

[samuelkarp]

samuelkarp force-pushed the buildsys-go-modules branch from 65bd339 to a7b439a

Added .gitignore files to the packages for the src/ directory that gets created during build.

[samuelkarp]

@bcressey Thanks for the detailed review here! I no longer work for Amazon and am not currently in a position to dedicate my own personal time or resources to moving this forward. I'd be happy for you or for someone else on the team to pick up my contribution and finish it. Please feel free to close this once a replacement PR is open.