bpf/selftests: Add selftests for token info

A previous change added bpf_token_info to get token info with
bpf_get_obj_info_by_fd, this patch adds a new test for token info.

 #461/12  token/bpf_token_info:OK

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Link: https://lore.kernel.org/r/20250716134654.1162635-2-chen.dylane@linux.dev


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