tunnel: T3786: Add checks for source any and not key

[sever-sever]

Change Summary

Additional check for gre tunnel if source address 0.0.0.0 and "key" not set.

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/T3786

Component(s) name

tunnel

Proposed changes

How to test

Should get warning about key:

set interfaces tunnel tun1 encapsulation gre
set interfaces tunnel tun1 source-address '0.0.0.0'
set interfaces tunnel tun1 address 10.10.10.1/30
set interfaces tunnel tun1 multicast 'enable'

vyos@r1-roll# commit
[ interfaces tunnel tun1 ]
Tunnel parameters ip key must be set!

[[interfaces tunnel tun1]] failed
Commit failed
[edit]
vyos@r1-roll# 

vyos@r1-roll# set interfaces tunnel tun1 parameters ip key 55
[edit]
vyos@r1-roll# commit
[edit]
vyos@r1-roll# 

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