volumes: support for api-socket volume type

[stevvooe]

What I did

The api-socket volume type allows an easy path to run containers that need access to the Docker API socket with a simple configuration on the service definition:

service:
  foo:
    ...
    volumes:
      - type: api-socket

The bind mount and credentials are automatically injected using existing service infrastructure. Some work is still needed to make this a bit more robust.

Related issue

docker/cli#5858
compose-spec/compose-go#770
compose-spec/compose-spec#587

(not mandatory) A picture of a cute animal, if possible in relation to what you did

[ndeloof]

For better alignment with docker CLI UX, we should b introduce a use_api_socket attribute in the compose spec.
I also wonder this is limited to unix socket. As implementation relies on DockerEndpoint().Host, running on Docker Desktop Windows the npipe:// URL will prevent use of this feature, while the actual engine in VM can expose a docker.sock to containers. Same applies to a remote docker engine accessed over ssh or http. I agree with docker/cli#5858 (comment) this should be a feature exposed by docker engine, not a hack by client code. At least this should be considered a temporary solution until engine has support for it