Feat(eos_designs): Add support for Port-Channels for WAN interfaces

[gmuloc]

Enhancement summary

Use the following schema in parallel of l3_interfaces under nodes

l3_port_channels:
  - id: 123
    mode: active
    ip_address: 1.2.3.4/23
    member_interfaces:
      - name: Ethernet12
        peer: <peer>
        peer_interface: <peer_interface>
        description: <description>
      - name: Ethernet13
        peer: <peer>
        peer_interface: <peer_interface>
        description: <description>

Need to add code in eos_designs and the tests

Which component of AVD is impacted

eos_designs

Use case example

WAN interfaces connecting via port-channel to Service Provider

Describe the solution you would like

cf summary

Describe alternatives you have considered

Can make it work using structured config today

Additional context

No response

Contributing Guide

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

[ClausHolbechArista]

l3_port_channels:
    # Port-Channel interface name like 'Port-Channel2' or subinterface name like 'Port-Channel2.42'.
    # For a Port-Channel subinterface, the parent Port-Channel interface must be defined as well.
  - name: <str; required; unique>
    
    # Port-Channel mode.
    mode: <str; "active" | "passive" | "on"; default="active">

    # Port-Channel member interfaces. Should not be set on Port-Channel subinterfaces.
    member_interfaces:
        # Ethernet interface name like 'Ethernet2' or subinterface name like 'Ethernet2.42'.
      - name: <str; required; unique>
        # The peer device name. Used for description and documentation.
        # If not set, this inherits the peer setting on the port-channel interface.
        peer: <str>

        # The peer device interface. Used for description and documentation.
        peer_interface: <str>

        # Speed should be set in the format `<interface_speed>` or `forced <interface_speed>` or `auto <interface_speed>`.
        speed: <str>

        # Custom structured config for the Ethernet interface.
        structured_config: <dict>

    # Node IPv4 address/Mask or 'dhcp'.
    ip_address: <str>

    # When the `ip_address` is `dhcp`, this optional field allows to indicate the expected
    # IPv4 address (without mask) to be allocated on the interface if known.
    # This is not rendered in the configuration but can be used for substitution of 'interface_ip' in the Access-list
    # set under `ipv4_acl_in` and `ipv4_acl_out`.
    dhcp_ip: <str>

    # Node IPv4 address (no mask).
    #
    # This is used to get the public IP (if known) when the device is behind NAT.
    # This is only used for `wan_rr` routers (AutoVPN RRs and Pathfinders) to determine the Public IP
    # with the following preference:
    #   `wan_route_servers.path_groups.interfaces.ip_address`
    #       -> `l3_interfaces.public_ip`
    #           -> `l3_interfaces.ip_address`
    #
    # The determined Public IP is used by WAN routers when peering with this interface.
    public_ip: <str>

    # For subinterfaces the dot1q vlan is derived from the interface name by default, but can also be specified.
    encapsulation_dot1q_vlan: <int; 1-4094>

    # Accept a default route from DHCP if `ip_address` is set to `dhcp`.
    dhcp_accept_default_route: <bool; default=True>

    # Enable or Shutdown the interface.
    enabled: <bool; default=True>

    # The peer device name. Used for description and documentation.
    peer: <str>

    # The peer device port-channel interface. Used for description and documentation.
    peer_port_channel: <str>

    # The peer device IPv4 address (no mask). Used as default route gateway if `set_default_route` is true and `ip` is an IP address.
    peer_ip: <str>

    # Enforce IPv4 BGP peering for the peer
    bgp:

      # BGP AS <1-4294967295> or AS number in asdot notation "<1-65535>.<0-65535>".
      # For asdot notation in YAML inputs, the value must be put in quotes, to prevent it from being interpreted as a float number.
      peer_as: <str; required>

      # Prefix List Name. Accept routes for only these prefixes from the peer.
      # Required for wan interfaces.
      ipv4_prefix_list_in: <str>

      # Prefix List Name. Advertise routes for only these prefixes.
      # If not specified, nothing would be advertised.
      ipv4_prefix_list_out: <str>

    # Name of the IPv4 access-list to be assigned in the ingress direction.
    # The access-list must be defined under `ipv4_acls` and supports field substitution for "interface_ip" and "peer_ip".
    # Required for all WAN interfaces (`wan_carrier` is set) unless the carrier is marked as 'trusted' under `wan_carriers`.
    ipv4_acl_in: <str>

    # Name of the IPv4 Access-list to be assigned in the egress direction.
    # The access-list must be defined under `ipv4_acls` and supports field substitution for "interface_ip" and "peer_ip".
    ipv4_acl_out: <str>

    # Configure IPv4 static routes pointing to `peer_ip`.
    static_routes: # >=1 items

        # IPv4_network/Mask.
      - prefix: <str; required>

    # QOS service profile.
    qos_profile: <str>

    # The WAN carrier this interface is connected to.
    # This is used to infer the path-groups in which this interface should be configured.
    # Unless the carrier is marked as 'trusted' under `wan_carriers`, `ipv4_acl_in` is also required on all WAN interfaces.
    wan_carrier: <str>

    # The WAN circuit ID for this interface.
    # This is not rendered in the configuration but used for WAN designs and descriptions.
    wan_circuit_id: <str>

    # For a WAN interface (`wan_carrier` is set), allow to disable the static tunnel towards Pathfinders.
    connected_to_pathfinder: <bool; default=True>

    # PREVIEW: This key is in preview mode
    cv_pathfinder_internet_exit:

      # List of Internet-exit policies using this interface as exit.
      policies:

          # Internet-exit policy name.
        - name: <str; required; unique>

          # Number range to use for Tunnel interfaces to an internet-exit service provider using this local interface.
          # Examples: '1-3' or '100,200,300'
          tunnel_interface_numbers: <str>

    # Configures flow-tracking on the interface. Overrides `fabric_flow_tracking.l3_port_channels` setting.
    flow_tracking:
      enabled: <bool>

      # Flow tracker name as defined in flow_tracking_settings.
      name: <str>

    # EOS CLI rendered directly on the port-channel interface in the final EOS configuration.
    raw_eos_cli: <str>

    # Custom structured config for the Port-Channel interface.
    structured_config: <dict>