tc: full JSON support for 'bpf' actions

tc: full JSON support for 'bpf' actions

Add full JSON output support in the dump of 'act_bpf'.

Example using eBPF:

 # tc actions flush action bpf
 # tc action add action bpf object bpf/action.o section 'action-ok'
 # tc -j action list action bpf | jq
 [
   {
     "total acts": 1
   },
   {
     "actions": [
       {
         "order": 0,
         "kind": "bpf",
         "bpf_name": "action.o:[action-ok]",
         "prog": {
           "id": 33,
           "tag": "a04f5eef06a7f555",
           "jited": 1
         },
         "control_action": {
           "type": "pipe"
         },
         "index": 1,
         "ref": 1,
         "bind": 0
       }
     ]
   }
 ]

Example using cBPF:

 # tc actions flush action bpf
 # a=$(mktemp)
 # tcpdump -ddd not ether proto 0x888e >$a
 # tc action add action bpf bytecode-file $a index 42
 # rm $a
 # tc -j action list action bpf | jq
 [
   {
     "total acts": 1
   },
   {
     "actions": [
       {
         "order": 0,
         "kind": "bpf",
         "bytecode": {
           "length": 4,
           "insns": [
             {
               "code": 40,
               "jt": 0,
               "jf": 0,
               "k": 12
             },
             {
               "code": 21,
               "jt": 0,
               "jf": 1,
               "k": 34958
             },
             {
               "code": 6,
               "jt": 0,
               "jf": 0,
               "k": 0
             },
             {
               "code": 6,
               "jt": 0,
               "jf": 0,
               "k": 262144
             }
           ]
         },
         "control_action": {
           "type": "pipe"
         },
         "index": 42,
         "ref": 1,
         "bind": 0
       }
     ]
   }
 ]

Tested with:
 # ./tdc.py -c bpf

Cc: Andrea Claudi <aclaudi@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David Ahern <dsahern@gmail.com>