c-v0.0.1 Docker image build fails due to missing git submodules

[acul71]

Problem

The c-v0.0.1 implementation Docker build fails with the following error:

CMake Error at CMakeLists.txt:99 (message):
  LIBP2P_VENDOR_PICOQUIC is ON, but the picoquic submodule is missing.  Run
  `git submodule update --init --recursive`.

Root Cause

The build process in transport/scripts/build-images.sh downloads GitHub repositories as zip archives when source.type: github. However, GitHub zip archives do not include git submodules, and the c-libp2p repository requires the picoquic submodule for the build to succeed.

The impls.yaml already has a requiresSubmodules: true flag for c-v0.0.1, but the build script doesn't handle this flag.

Solution

The build script should detect when requiresSubmodules: true is set and use git clone instead of downloading a zip archive. The fix should:

1. Check for requiresSubmodules: true flag in the implementation configuration
2. Use git clone instead of zip download when submodules are required
3. Checkout the specific commit
4. Run git submodule update --init --recursive to initialize submodules
5. Cache the cloned repository for future builds

Steps to Reproduce

cd transport
./run_tests.sh --cache-dir ~/.cache/test-plans --test-select 'c-v0.0.1' --test-ignore '!c-v0.0.1' --force-image-rebuild --yes

Expected Behavior

The Docker image should build successfully with all required submodules initialized.

Actual Behavior

The build fails during CMake configuration because the picoquic submodule is missing.

[acul71]

fix in #760

[dhuseby]

Reopening due to revert.