ClatdController - add oifIsEthernet field to struct ClatEgressValue

Afterwards on a phone with both cellular and wifi ipv6 only connectivity:

$ adb shell dumpsys netd | sed -rn '/^  ClatdController$/,/^$/p'

  ClatdController
    Trackers: iif[iface] nat64Prefix v6Addr -> v4Addr v4iif[v4iface] [netId]
      11[rmnet_data1] 2607:7700:0:1c:0:1::/96 2607:fb90:271f:f614:2732:a1bf:4c29:cef8 -> 192.0.0.4 33[v4-rmnet_data1] [101]
      30[wlan0] 64:ff9b::/96 2401:fa00:480:13d:9ba4:e8a9:1e01:f9f6 -> 192.0.0.5 34[v4-wlan0] [100]
    BPF ingress map: iif(iface) nat64Prefix v6Addr -> v4Addr oif(iface)
      30(wlan0) 64:ff9b::/96 2401:fa00:480:13d:9ba4:e8a9:1e01:f9f6 -> 192.0.0.5 34(v4-wlan0)
      11(rmnet_data1) 2607:7700:0:1c:0:1::/96 2607:fb90:271f:f614:2732:a1bf:4c29:cef8 -> 192.0.0.4 33(v4-rmnet_data1)
    BPF egress map: iif(iface) v4Addr -> v6Addr nat64Prefix oif(iface)
      34(v4-wlan0) 192.0.0.5 -> 2401:fa00:480:13d:9ba4:e8a9:1e01:f9f6 64:ff9b::/96 30(wlan0) ether
      33(v4-rmnet_data1) 192.0.0.4 -> 2607:fb90:271f:f614:2732:a1bf:4c29:cef8 2607:7700:0:1c:0:1::/96 11(rmnet_data1) rawip

Test: compiles, atest, flashed to phone on wifi/cellular ipv6 only
      network and observed dumpsys netd printout
Bug: 139396664
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I98ec30cd2fd282997aadc4582f472a224a02c607