Support for platform fap buffering command

[dgonzalez85]

Enhancement summary

We are looking to replicate AI deployment.

By default the R3 platforms have buffers balanced across both multicast and unicast queues. Multicast is not in use a therefore the egress buffer profile is changed to “unicast” to adjust the buffers in favor of unicast traffic. This can be done with:

platform fap buffering egress profile unicast

(config)#platform fap buffering egress profile ?
  balanced  equal unicast and multicast buffers
  unicast   increase unicast buffers

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

Which component of AVD is impacted

eos_cli_config_gen

Use case example

AI deployments that require to adjust buffers in favour of unicast buffers in R3 platforms.

Describe the solution you would like

Add support to configure this command in the platform section.

Describe alternatives you have considered

custom_structured_configuration_eos_cli: |
platform fap buffering egress profile unicast

Additional context

No response

Contributing Guide

• I agree to follow this project's Code of Conduct