bpftool: Support new prog types and attach types

Add recently added prog types to `bpftool prog` and attach types to
`bpftool cgroup`.

Update bpftool documentation and bash completion appropriately.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>