T6792: Autocomplete for "show arp interface" interfaces

[HollyGurza]

Change Summary

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://vyos.dev/T6792

Related PR(s)

Component(s) name

Proposed changes

How to test

vyos@vyos:~$ show arp interface 
Possible completions:
  dum1                  Show Address Resolution Protocol (ARP) cache for specified
                        interface
  eth0
  eth1
  eth2
  eth3
  lo

      
vyos@vyos:~$ show arp interface lo 
Address    Interface    Link layer address    State
---------  -----------  --------------------  -------

Smoketest result

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

[github-actions]

👍
No issues in PR Title / Commit Title

[github-actions]

CI integration ❌ failed!

Details

CI logs

• CLI Smoketests (no interfaces) ❌ failed
• CLI Smoketests (interfaces only) 👍 passed
• Config tests 👍 passed
• RAID1 tests 👍 passed
• TPM tests 👍 passed

[dmbaturin]

I don't think we should show all interfaces there. There's no ARP on IPIP, IP6IP, loopback, dummies, VTI... if list_interfaces --broadcast doesn't show all interfaces with a broadcast flag, we need to fix the list_interfaces script.

If that's an intractable problem (which I doubt), we should limit this list to interfaces that we know can send and receive ARP.

[HollyGurza]

implemented here: vyos/vyos-utils#28