Add H4PacketizerSources filegroup

bt_vhci_forwarder in cuttlefish doesn't need to full implementation of
rootcanal, it needs only h4 packetizer implementation.

Bug: 195692688
Test: launch_cvd and then check bluetooth feature in cf.
Change-Id: I25aa5f1a2e815703de3beb59ffebf148309baec6