ClatCoordinator: use Java class BpfMap to remove clat rule

This a preparation to replace duplicated native functions with the
existing Java class.

Bug: 221213090
Test: atest FrameworksNetTests
Test: manual check

Steps:
1. Connect wlan and check map content {iface index, v4addr, v6addr, pfx96} manually
after clat started.
$ adb shell dumpsys netd
  ClatdController
    BPF ingress map: iif(iface) nat64Prefix v6Addr -> v4Addr oif(iface)
      47(wlan0) 64:ff9b::/96 2a00:79e1:abc:6f02:2479:2f51:25a9:28f1 -> 192.0.0.4 53(v4-wlan0)
    BPF egress map: iif(iface) v4Addr -> v6Addr nat64Prefix oif(iface)
      53(v4-wlan0) 192.0.0.4 -> 2a00:79e1:abc:6f02:2479:2f51:25a9:28f1 64:ff9b::/96 47(wlan0) ether

2. Disconnect wlan and check the bpf map is removed.
$ adb shell dumpsys netd
  ClatdController
    BPF ingress map: iif(iface) nat64Prefix v6Addr -> v4Addr oif(iface)
    BPF egress map: iif(iface) v4Addr -> v6Addr nat64Prefix oif(iface)

Change-Id: Ia0c90c7104c4a42d34a28a5ddf3cf13a289f8c76
3 files changed