Add bpf_wq selftests to verify: * BPF program using non-constant offset of struct bpf_wq is rejected * BPF program using map with no BTF for storing struct bpf_wq is rejected Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Tested-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20251010164606.147298-2-mykyta.yatsenko5@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>