containers: T4585: Add option restart to containers.py

[sever-sever]

Change Summary

Add option restart to containers.py

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://phabricator.vyos.net/T4585

Component(s) name

containers

Proposed changes

How to test

vyos@r14:~$ /usr/libexec/vyos/op_mode/container.py restart --name alp01
Container name "alp01" restarted!
vyos@r14:~$ 
vyos@r14:~$ /usr/libexec/vyos/op_mode/container.py restart --name alp02
Error: no container with name or ID alp02 found: no such container
vyos@r14:~$ 

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly