feat(anta.tests): Add new BGP tests

[carl-baillargeon]

Description

• Add the following BGP tests:

anta.tests.routing:
  bgp:
    - VerifyBGPPeerCount:
        address_families:
          - afi: "evpn"
            num_peers: 2
          - afi: "ipv4"
            safi: "unicast"
            vrf: "PROD"
            num_peers: 2
          - afi: "ipv4"
            safi: "unicast"
            vrf: "default"
            num_peers: 3
          - afi: "ipv4"
            safi: "unicast"
            vrf: "all"
            num_peers: 5
          - afi: "ipv4"
            safi: "multicast"
            vrf: "DEV"
            num_peers: 3

    - VerifyBGPPeersHealth:
        address_families:
          - afi: "evpn"
          - afi: "ipv4"
            safi: "unicast"
            vrf: "default"
          - afi: "ipv6"
            safi: "unicast"
            vrf: "DEV"
    
    - VerifyBGPSpecificPeer:
        address_families:
          - afi: "evpn"
            peers:
              - 10.1.0.1
              - 10.1.0.2
          - afi: "ipv4"
            safi: "unicast"
            peers:
              - 10.1.254.1
              - 10.1.255.0
              - 10.1.255.2
              - 10.1.255.4

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have run pre-commit for code linting and typing (pre-commit run)
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes (tox -e testenv)
• Add a note to existing BGP tests for deprecation in a future release