Add tunnel underlay vrf as key for the tunnel_interfaces in eos_cli_config_gen model

[dkeitaarista]

Enhancement summary

Right the command "tunnel underlay vrf <...>" is not available in eos_cli_config_gen model therefore it can be rendered on a tunnel interface only by using eos_cli. A Customer IT would like to have this command to be in AVD eos_cli_config_gen model for a tunnel interface without using eos_cli. See below an example of config being currently used.

tunnel_interfaces:

• name: Tunnel2
  description: "[L]EHS Tunnel to iqdrr90-91-tu720"
  shutdown: false
  vrf: ehs
  ip_address: 10.75.255.174/30
  source_interface: Loopback3
  destination: 172.16.173.33
  eos_cli: |
  tunnel underlay vrf IT
• name: Tunnel3
  description: "[L]GNET Tunnel to iqdrr90-91-tu280"
  shutdown: false
  vrf: Gnet
  ip_address: 10.70.253.222/30
  source_interface: Loopback2
  destination: 172.16.173.65
  eos_cli: |
  tunnel underlay vrf IT

Which component of AVD is impacted

eos_cli_config_gen

Use case example

Being able to define tunnel underlay vrf without using eos_cli as being currently done.
tunnel_interfaces:

• name: Tunnel2
  description: "[L]EHS Tunnel to iqdrr90-91-tu720"
  shutdown: false
  vrf: ehs
  ip_address: 10.75.255.174/30
  source_interface: Loopback3
  destination: 172.16.173.33
  eos_cli: |
  tunnel underlay vrf IT
• name: Tunnel3
  description: "[L]GNET Tunnel to iqdrr90-91-tu280"
  shutdown: false
  vrf: Gnet
  ip_address: 10.70.253.222/30
  source_interface: Loopback2
  destination: 172.16.173.65
  eos_cli: |
  tunnel underlay vrf IT

Describe the solution you would like

Add underlay_vrf as key for a tunnel_interfaces variables of eos_cli_config_gen.

Describe alternatives you have considered

No response

Additional context

No response

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