refactor!: drop the Docker model

DockerInfoDict, DockerContainerDict, DockerImageDict, DockerVolumeDict,
DockerNetworkDict and the OSDriver declaration of get_docker_info() go.
They described napalm-linux' old CLI reading, which napalm-linux 0.3.0
dropped. There is no container model here: netOrk reads and handles
containers over the Engine API (NetOrk/netork#765, phase 9); this
package only gives access to the engine.

Version 4.0.0.

tests/test_container_engine.py

@@ -157,3 +157,22 @@ class TestPrivilegedCli:
         driver.open_container_engine("docker").stream_cli(["pull", "nginx"], privileged=True)
 
         assert driver.streams == [("docker pull nginx", True)]
+
+
+class TestNoDockerModel:
+    """There is no container model here (NetOrk/netork#765): netOrk reads and
+    handles containers over the Engine API, so the CLI-shaped types and the
+    ``get_docker_info()`` declaration that served napalm-linux' old reading are gone."""
+
+    def test_the_docker_types_are_gone(self):
+        import napalm_device_types
+        from napalm_device_types import models
+
+        for name in ("DockerInfoDict", "DockerContainerDict", "DockerImageDict"):
+            assert not hasattr(models, name), name
+            assert not hasattr(napalm_device_types, name), name
+
+    def test_an_os_driver_declares_no_docker_reading(self):
+        from napalm_device_types import os as os_role
+
+        assert "get_docker_info" not in os_role.__dict__.get("OSDriver", object).__dict__