Pull persistent connection parameters via get_option (#39367)

* WIP Pull persistent connection parameters via get_option

* Fix pep8

* Add use_persistent_connection setting to paramiko_ssh plugin

* Add vars section to persistent_command_timeout setting and prevail provider values over config manager

* Use persistent_command_timeout on network_cli instead of timeout

* Fix unit tests

If we don't call loader to get network_cli, then _load_name is never
set and we get KeyError.

* Pull persistent_command_timeout via config  manager for ios connection local

* Pull persistent_command_timeout via config manager on connection local

lib/ansible/plugins/connection/persistent.py

@@ -6,12 +6,26 @@ from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
 DOCUMENTATION = """
-    author: Ansible Core Team
-    connection: persistent
-    short_description: Use a persistent unix socket for connection
+author: Ansible Core Team
+connection: persistent
+short_description: Use a persistent unix socket for connection
+description:
+  - This is a helper plugin to allow making other connections persistent.
+version_added: "2.3"
+options:
+  persistent_command_timeout:
+    type: int
     description:
-        - This is a helper plugin to allow making other connections persistent.
-    version_added: "2.3"
+      - Configures, in seconds, the amount of time to wait for a command to
+        return from the remote device.  If this timer is exceeded before the
+        command returns, the connection plugin will raise an exception and
+        close
+    default: 10
+    ini:
+      - section: persistent_connection
+        key: command_timeout
+    env:
+      - name: ANSIBLE_PERSISTENT_COMMAND_TIMEOUT
 """
 import os
 import pty