bpf: Add support for kprobe session attach

Adding support to attach bpf program for entry and return probe
of the same function. This is common use case which at the moment
requires to create two kprobe multi links.

Adding new BPF_TRACE_KPROBE_SESSION attach type that instructs
kernel to attach single link program to both entry and exit probe.

It's possible to control execution of the bpf program on return
probe simply by returning zero or non zero from the entry bpf
program execution to execute or not the bpf program on return
probe respectively.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240430112830.1184228-2-jolsa@kernel.org