selftests/bpf: add tests for the bpf_numab_ops struct_ops

新增 bpf_numab_ops struct_ops 自测，在 prog_tests/progs 中构造 attach/detach 计数器、层级聚合、多策略组合、继承和 surface dispatch 五类场景，验证注册注销、层叠与策略分发正确。