core, bpf: add socket-bind feature to unit

core, bpf: add socket-bind feature to unit

Add supported and install unit interface for socket-bind feature.

supported verifies that
- unified cgroup hierarchy (cgroup v2) is used
- BPF_FRAMEWORK (libbpf + clang + llvm + bpftool) was available in
compile time
- kernel supports BPF_PROG_TYPE_CGROUP_SOCK_ADDR
- bpf programs can be loaded into kernel
- bpf link can be used

install:
- load bpf_object from bpf skeleton
- resize rules map to fit socket_bind_allow and socket_bind deny rules
from cgroup context
- populate cgroup-bpf maps with rules
- get bpf programs from bpf skeleton
- attach programs to unit cgroup using bpf link
- save bpf link in the unit