* Add sros changes for Python3
Make `execute_command` arguments and its
return value complaint to PY3 changes
made in PR #24431
Code cleanup
pep8 fixes
* Fix CI issue
* fixes action handlers for sros
* fixes sros_config module execution to use AnsibleModule
* fixes sros_command module to use socket connection
* adds sros to constants
* removes unneeded supports_multiplexing var
* refactors terminal_prompts_re to terminal_stdout_re
* refactors terminal_errors_re to terminal_stderr_re
* updates network_cli unit test cases
* adds new connection plugin `network_cli` which builds on paramiko
* adds new plugin `terminal` used for manipulating network_cli terminals
* adds new field to play_context `network_os` settable as ansible_network_os
This commit adds the plugins necesary to establish a persistent cli connection
to network devices of ssh. It builds on the paramiko connection plugin
to create a shell environment that will persistent through ansible-connection.
The `newtork_cli` plugin then uses the network_os in the instance of
PlayContext to load the appropriate network OS environment plugin for
handling opening and closing of shells as well as privilege escalation.
Roman Dodin
Peter Sprygada
Ganesh Nalawade