adds config option to auto add keys when using paramiko (#18598)

* updates paramiko_ssh to auto add keys
* updates constants with new config options

This commit adds a new feature that will allow paramiko to automatically
accept and save a host ssh key.  This feature is controlled by the
`host_key_auto_add` config setting in the paramiko section.  The default
is False to maintain current functionality.  It also includes a new
setting `look_for_keys` with the default to False for maintaining current the
current setting.

lib/ansible/plugins/connection/paramiko_ssh.py

@@ -89,7 +89,10 @@ class MyAddPolicy(object):
 
     def missing_host_key(self, client, hostname, key):
 
-        if C.HOST_KEY_CHECKING:
+        if all((C.HOST_KEY_CHECKING, not C.PARAMIKO_HOST_KEY_AUTO_ADD)):
+
+            if C.USE_PERSISTENT_CONNECTIONS:
+                raise AnsibleConnectionFailure('rejected %s host key for host %s: %s' % (key.get_name(), hostname, hexlify(key.get_fingerprint())))
 
             self.connection.connection_lock()
 
@@ -227,7 +230,7 @@ class Connection(ConnectionBase):
                 self._play_context.remote_addr,
                 username=self._play_context.remote_user,
                 allow_agent=allow_agent,
-                look_for_keys=True,
+                look_for_keys=C.PARAMIKO_LOOK_FOR_KEYS,
                 key_filename=key_filename,
                 password=self._play_context.password,
                 timeout=self._play_context.timeout,