Now we have the following ways to set additional arguments:

1. [ssh_connection]ssh_args in ansible.cfg: global setting, prepended to
   every command line for ssh/scp/sftp. Overrides default ControlPersist
   settings.
2. ansible_ssh_common_args inventory variable. Appended to every command
   line for ssh/scp/sftp. Used in addition to ssh_args, if set above, or
   the default settings.
3. ansible_{sftp,scp,ssh}_extra_args inventory variables. Appended to
   every command line for the relevant binary only. Used in addition to
   #1 and #2, if set above, or the default settings.
3. Using the --ssh-common-args or --{sftp,scp,ssh}-extra-args command
   line options (which are overriden by #2 and #3 above).

This preserves backwards compatibility (for ssh_args in ansible.cfg),
but also permits global settings (e.g. ProxyCommand via _common_args) or
ssh-specific options (e.g. -R via ssh_extra_args).

Fixes #12576