Download mc/minio executables if necessary

[alexandertuna]

A todo list:

• Add logic to CMakeLists.txt
• Specify to the tests via an environment variable
• Add tests?

Test cases I've run:

• Checking for minio/mc and downloading if they don't exist
  • macos arm64
  • ubuntu arm64
  • ubuntu amd64
• Running the tests
  • macos arm64, minio/mc already exist
  • macos arm64, minio/mc don't exist

[bbockelm]

Existing code looks good.

However, in distro build environments (e.g., RPMs for EPEL), there's no available network connectivity and this would now cause their builds to fail.

I see two options:

1. Do not make MINIO_BIN and MC_BIN required and allow the unit tests to fail. Downstream packagers will have to hand-label tests to skip.
2. Add explicit CMake logic that skips tests or activities (such as mc download) that require network connectivity.

[alexandertuna]

Thanks @bbockelm!

I'm confused about the network situation, can you help me understand? Are you saying the build should succeed without minio/mc (in the absence of network) because they're not a compilation dependency, even if the runtime will fail?

[bbockelm]

LGTM!