Remove requireNonNull check from matchesWifiNetworkKey

matchesWifiNetworkKey expects a non-null value of the
wifiNetworkKey, however, it might be null in practice
and the null wifiNetworkKey will be stored into disk.
And then when the matchesWifiNetworkKey is called, the
requireNonNull will crash the system. Thus, remove the
requireNonNull from matchesWifiNetworkKey to avoid
system crash and handle if the wifiNetworkKey is null
then it should not match a template with non-empty
mMatchWifiNetworkKeys.

Check if WifiInfo contains a null network key then skip it
to prevent adding the identity to the network identity set.
Also, add a Log.wtf when setWifiNetworkKey(info.getNetworkKey()),
this might be useful to catch why the wifiNetworkKey is
null.

Bug: 267815242
Bug: 266598304
Test: FrmeworksNetTests
Change-Id: I9c21f7e3dca9482133c7e331741cf808105414e9