build docker images from logstash repo (#10603)

introduces two rake tasks: `rake artifact:docker_oss` and `rake artifact:docker`, which will create the docker images of the OSS and non OSS packages. These tasks depend on the tar artifacts being built.

Also `rake artifact:all` has been modified to also call these two tasks.

most code was moved from https://github.com/elastic/logstash-docker/

docker/tests/conftest.py

@@ -0,0 +1,25 @@
+from subprocess import run
+import pytest
+from .constants import container_name, version
+import docker
+
+docker_engine = docker.from_env()
+
+
+def pytest_addoption(parser):
+    """Customize testinfra with config options via cli args"""
+    # Let us specify which docker-compose-(image_flavor).yml file to use
+    parser.addoption('--image-flavor', action='store', default='full',
+                     help='Docker image flavor; the suffix used in docker-compose-<flavor>.yml')
+
+
+@pytest.fixture(scope='session', autouse=True)
+def start_container():
+    image = 'docker.elastic.co/logstash/logstash-%s:%s' % (pytest.config.getoption('--image-flavor'), version)
+    docker_engine.containers.run(image, name=container_name, detach=True, stdin_open=False)
+
+
+def pytest_unconfigure(config):
+    container = docker_engine.containers.get(container_name)
+    container.stop()
+    container.remove()