Add stage to count packet processing results

[Fredi-raspall]

• Defines type PacketStats, which is a vector of atomicU64's indexed by DoneReason
• Implements PacketStatsNF and adds it to the pipeline
• Add cli command to show counts per DoneReason.
• Redefine some DoneReasons for clarity

dataplane(✔)# show packet stats
 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Packet stats ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    Packet result                  count
    Internal failure               0
    Interface: unknown             10
    Interface: detached            0
    Interface: admin down          0
    Interface: oper down           0
    Interface: unsupported         0
    Not Ethernet                   0
    Unhandled                      2
    Frame not for us               289
    Invalid dst MAC                0
    Missing ether type             0
    Filtered                       0
    IP:  packet is not IP          2
    IP:  missing routing info      0
    IP:  route drop                17
    IP:  TTL exceeded              0
    IP:  L2 resolution failure     0
    NAT: out of resources          0
    NAT: Unsupported protocol      0
    NAT: failure                   0
    NAT: not port-forwarded        0
    Malformed packet               0
    Unroutable                     0
    Invalid checksum               0
    Incomplete ICMP error          0
    Internal drop                  0
    Locally delivered              200
    Delivered                      311611