714b786585
Currently NAT64 prefix discovery, which runs in netd, is started by netd itself when a network is programmed with all-IPv6 DNS servers. Unfortunately this is not correct because in many cases we program DNS servers before the network is connected and it's actually possible to send packets to them. In general netd does not have enough visibility into network lifecycle management to decide when to start and stop prefix discovery. So move it into the framework with the rest of the 464xlat control plane. Bug: 65674744 Test: atest FrameworksNetTests Change-Id: I8fa051a9c216d9c05082bf7d0bbb0cbd56000162