[NETD-BPF#6] Move bpf_shared.h from netd to module

Refers to bpf_connectivity_headers where the bpf_shared.h is located.

Bug: 202086915
Test: m; flash; boot
Test: cd system/netd && atest
Test: cd packages/modules/Connectivity && atest
Test: atest FrameworksNetTests
Change-Id: I3dd780470f136926680542f4571a2d130451497d