bpftool: Extend net dump with tcx progs

Add support to dump fd-based attach types via bpftool. This includes both
the tc BPF link and attach ops programs. Dumped information contain the
attach location, function entry name, program ID and link ID when applicable.

Example with tc BPF link:

  # ./bpftool net
  xdp:

  tc:
  bond0(4) tcx/ingress cil_from_netdev prog_id 784 link_id 10
  bond0(4) tcx/egress cil_to_netdev prog_id 804 link_id 11

  flow_dissector:

  netfilter:

Example with tc BPF attach ops:

  # ./bpftool net
  xdp:

  tc:
  bond0(4) tcx/ingress cil_from_netdev prog_id 654
  bond0(4) tcx/egress cil_to_netdev prog_id 672

  flow_dissector:

  netfilter:

Currently, permanent flags are not yet supported, so 'unknown' ones are dumped
via NET_DUMP_UINT_ONLY() and once we do have permanent ones, we dump them as
human readable string.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/20230719140858.13224-7-daniel@iogearbox.net


Signed-off-by: Alexei Starovoitov <ast@kernel.org>