Support to configure MTU values for fwd interfaces

[dgonzalez85]

Enhancement summary

We are looking to replicate AI deployment.

This feature provides the ability to configure the MTU value of fwd devices in a specific vrf or across vrfs:
https://www.arista.com/en/support/toi/eos-4-26-0f/14721-configurable-mtu-values-for-fwd-interfaces

router general
  software forwarding hardware offload mtu <val>

(config)#software forwarding hardware offload mtu ?
  <68-10210>  MTU value

But its not supported:
https://avd.arista.com/5.1/roles/eos_cli_config_gen/docs/input-variables.html#router-general

Which component of AVD is impacted

eos_cli_config_gen

Use case example

Used in conjunction with large packet size in connectivity monitor.

Describe the solution you would like

Add support to configure this command in the router general section.

Describe alternatives you have considered

none

Additional context

No response

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