Rename docker execution module to avoid shadowing in the loader

With the merging of #39996, salt/modules/docker.py now imports
salt.utils.docker. However, our loader appends the module dir (in
this case salt/modules/) to sys.path temporarily for the length of the
loading process. So, as the docker execution module tries to import
salt.utils.docker, when salt.utils.docker attempts to do an "import
docker", and docker-py is *not* installed, this results in
salt/modules/docker.py (the docker execution module) being loaded in its
place, which results in tracebacks in the minion log.

Renaming the docker execution module keeps this import shadowing from
occurring. Note that we don't need to do this for the placeholder
salt/states/docker.py as it does not import salt.utils.docker.

doc/ref/modules/all/index.rst

@@ -109,7 +109,7 @@ execution modules
     dnsmasq
     dnsutil
     dockercompose
-    docker
+    dockermod
     dpkg
     drac
     dracr

doc/ref/modules/all/salt.modules.docker.rst

@@ -1,7 +0,0 @@
-===================
-salt.modules.docker
-===================
-
-.. automodule:: salt.modules.docker
-    :members:
-    :exclude-members: cp, freeze, unfreeze

doc/ref/modules/all/salt.modules.dockermod.rst

@@ -0,0 +1,7 @@
+======================
+salt.modules.dockermod
+======================
+
+.. automodule:: salt.modules.dockermod
+    :members:
+    :exclude-members: cp, freeze, unfreeze

tests/unit/modules/test_dockermod.py

@@ -19,7 +19,7 @@ from tests.support.mock import (
 # Import Salt Libs
 from salt.ext.six.moves import range
 from salt.exceptions import CommandExecutionError
-import salt.modules.docker as docker_mod
+import salt.modules.dockermod as docker_mod
 
 docker_mod.__context__ = {'docker.docker_version': ''}
 docker_mod.__salt__ = {}

tests/unit/states/test_docker_image.py

@@ -17,7 +17,7 @@ from tests.support.mock import (
 
 # Import Salt Libs
 from salt.exceptions import CommandExecutionError
-import salt.modules.docker as docker_mod
+import salt.modules.dockermod as docker_mod
 import salt.states.docker_image as docker_state
 
 docker_mod.__context__ = {'docker.docker_version': ''}

tests/unit/states/test_docker_network.py

@@ -16,7 +16,7 @@ from tests.support.mock import (
 )
 
 # Import Salt Libs
-import salt.modules.docker as docker_mod
+import salt.modules.dockermod as docker_mod
 import salt.states.docker_network as docker_state
 
 docker_mod.__context__ = {'docker.docker_version': ''}

tests/unit/states/test_docker_volume.py

@@ -16,7 +16,7 @@ from tests.support.mock import (
 )
 
 # Import Salt Libs
-import salt.modules.docker as docker_mod
+import salt.modules.dockermod as docker_mod
 import salt.states.docker_volume as docker_state
 
 docker_mod.__context__ = {'docker.docker_version': ''}