Move isChainEnabled and getUidRule to BpfNetMapsUtils

This CL also adds @RequiresApi(Build.VERSION_CODES.UPSIDE_DOWN_CAKE)
to NetworkStackBpfNetMaps

Bug: 328732146
Test: TH
Change-Id: Ifa4cffd046164405b8b49d2e2ee9f27240bec6fa
3 files changed