Fix(eos_cli_config_gen): Port-channel can use LACP fallback configuration on physical interface

[xaviramon]

Change Summary

In order to use LACP fallback feature, it iw requested that physical interface of a Port-channel has specific and different configuration than the PC itself.
Under this PR, a new validation is set under the ethernet interfaces where a flag is used to decide if configuration under the physical interface must be rendered or not.

Related Issue(s)

Fixes #1279

Component(s) name

arista.avd.eos_cli_config_gen

Proposed changes

The flag checks if the interface is a Port-channel. If not, flag is activated and configuration is rendered.
If the interface is a Port-channel, it is verified if LACP individual mode is defined. In this case, flag is activated and configuration will be rendered. For normal PC with no LACP fallback individual, flag is not activated and configuration is not rendered.
This is the way that introduces less changes while keeping the previous behaviour.

How to test

Molecule test included

Checklist

User Checklist

• N/A

Repository Checklist

• My code has been rebased from devel before I start
• I have read the CONTRIBUTING document.
• My change requires a change to the documentation and documentation have been updated accordingly.
• I have updated molecule CI testing accordingly. (check the box if not applicable)

[ClausHolbechArista]

LGTM

[tgodaA]

LGTM!