Add oem-iptables-init.sh for Wi-Fi calling in airplane mode
This was added recently in Android 15, see the following commit:
https://android.googlesource.com/device/google/gs101/+/fbf009b886cb6391b0833ab147a18c4cf9adda0d
Issue: calyxos#2813
Change-Id: I853f087347795e1d8932db2020f8a69fb5d97fa6