Is your feature request related to a problem? Please describe.
When building a container we need access to other Resources like ssh and dont want to expose a private key in the container.

Describe the solution you'd like
Support of --ssh in the build process that already works in buildkit.

Additional context
I tried 1.25.0-rc4, but it does not support --ssh option. Tried the same as in bug 6440:

export COMPOSE_DOCKER_CLI_BUILD=1
export DOCKER_BUILDKIT=1
docker-compose build --ssh default my_image

This would be a major security improvement and save us so much pain.

Thanks,
bert