dhcp-server: T7723: add DHCP Option 26 (interface MTU)

[mzpqnxow]

Change summary

Support DHCP v4 option 26 - interface MTU

• Add interface-mtu to option-v4.xml.i
• Add interface_mtu -> interface-mtu translation in python/vyos/kea.py
• Add to smoke tests

Note, I have not actually run the smoke tests yet, I need to set up an environment to test in

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/T7723

Related PR(s)

None

How to test / Smoketest result

Enhancements were made to the existing test_service_dhcp-server.py script. I have not tested yet as I don't have an environment set up

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 VPP ❌ failed
• CLI Smoketests (interfaces only) ❌ failed
• Config tests ❌ failed
• Config tests VPP ❌ failed
• RAID1 tests ❌ failed
• TPM tests ❌ failed