"cacheFrom" value not considered when building dev container features

The build.cacheFrom value allows you to publish an image, and then use it as a local cache for subsequent builds on another machine (as does the Docker Compose equivalent). Currently contents of the image in cacheFrom do not appear to be being used during the dev container features build step which reduces the utility of it pretty significantly.

Repro:

1. Go to https://github.com/chuxel/feature-library and create a Codespace, or clone the project locally and create a dev container from it
2. Watch the Dockerfile build

Expected: Since there is a pre-built image with the “docker-in-docker” feature inside it (see https://github.com/Chuxel/feature-library/blob/main/.github/workflows/devcontainer-image.yaml), the feature docker build reuses the cached result. Actual: The image contents are only used in during the core Dockerfile build not during the feature build

Log section illustrating the cache being used in one case, but not the other.

2022-08-31 19:41:33.478Z: #14 [dev_container_auto_added_stage_label 2/2] RUN su node -c "npm install -g @devcontainers/cli"
2022-08-31 19:41:33.758Z: #14 pulling sha256:0df7bb7c7da4a5becc4ee99cdb66cc9175a54cc0d860b26de69a7376b687e6a9
2022-08-31 19:41:34.206Z: #14 pulling sha256:0df7bb7c7da4a5becc4ee99cdb66cc9175a54cc0d860b26de69a7376b687e6a9 0.4s done
2022-08-31 19:41:38.855Z: #14 CACHED
2022-08-31 19:41:38.997Z: 
2022-08-31 19:41:38.997Z: #15 [dev_containers_target_stage 1/2] COPY --from=dev_containers_feature_content_source . /tmp/build-features/
2022-08-31 19:41:39.107Z: #15 DONE 0.2s
2022-08-31 19:41:39.246Z: 
2022-08-31 19:41:39.247Z: #16 [dev_containers_target_stage 2/2] RUN cd /tmp/build-features/docker-in-docker_1 && export $(cat devcontainer-features.env | xargs) && chmod +x ./install.sh && ./install.sh
2022-08-31 19:42:45.745Z: #16 66.46 DOCKER_MOBY_ARCHIVE_VERSION_CODENAMES=buster bullseye bionic focal jammy
2022-08-31 19:42:45.745Z: #16 66.46 Distro codename  'bullseye'  matched filter  'buster bullseye bionic focal jammy'
2022-08-31 19:42:45.745Z: #16 66.47 Running apt-get update...
2022-08-31 19:42:45.884Z: #16 66.76 Get:1 http://deb.debian.org/debian bullseye InRelease [116 kB]
2022-08-31 19:42:46.022Z: #16 66.78 Get:2 http://deb.debian.org/debian-security bullseye-security InRelease [48.4 kB]
2022-08-31 19:42:46.022Z: #16 66.78 Get:3 http://deb.debian.org/debian bullseye-updates InRelease [44.1 kB]
2022-08-31 19:42:46.022Z: #16 66.79 Get:4 https://dl.yarnpkg.com/debian stable InRelease [17.1 kB]
```

[Chuxel]

@davidwallacejackson Sorry for the delay! @chrmarti and I have been out-of-office, but @jkeech mentioned @edgonmsft, @joshspicer, or @samruddhikhandale could look at https://github.com/devcontainers/cli/pull/233 @stuartleeks took a quick look as well and it looked good.

[davidwallacejackson]

Made a PR with this change and tested it manually – looks like this does, in fact, solve the problem!