T8104 static routes multiple next-hop targets

[omnom62]

Change Summary

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [x] 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/T8104

Related PR(s)

Component(s) name

Proposed changes

How to test

Test results

• [x] Sanity tests passed
• [x] Unit tests passed

Tested against VyOS versions:

• 1.4.2
• 1.5Q2

Checklist:

• [x] I have read the CONTRIBUTING document
• [x] I have linked this PR to one or more Phabricator Task(s)
• [x] I have run the ansible sanity and unit tests
• [x] My commit headlines contain a valid Task id
• [ ] My change requires a change to the documentation
• [ ] I have updated the documentation accordingly
• [ ] I have added unit tests to cover my changes
• [x] I have added a file to changelogs/fragments to describe the changes