selftests/bpf: Add uretprobe syscall test for regs integrity

selftests/bpf: Add uretprobe syscall test for regs integrity

Add uretprobe syscall test that compares register values before
and after the uretprobe is hit. It also compares the register
values seen from attached bpf program.

Link: https://lore.kernel.org/all/20240611112158.40795-6-jolsa@kernel.org/
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>