bpf: Add cookies support for uprobe_multi link

bpf: Add cookies support for uprobe_multi link

Adding support to specify cookies array for uprobe_multi link.

The cookies array share indexes and length with other uprobe_multi
arrays (offsets/ref_ctr_offsets).

The cookies[i] value defines cookie for i-the uprobe and will be
returned by bpf_get_attach_cookie helper when called from ebpf
program hooked to that specific uprobe.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230809083440.3209381-5-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>