Add a default apn-conf.xml into GSI

Add a default apn-conf.xml for telephony data network, then some
devices, ex. emulator, could use the default setting when it's
system image overrided by GSI.

Bug: 69869274
Test: build pass and boot a Pixel device with GSI to home screen
Change-Id: I0275a5d420eadcbb2f744e995c9a72a1fb46b935
diff --git a/target/product/treble_common.mk b/target/product/treble_common.mk
index 13b7769..d406d32 100644
--- a/target/product/treble_common.mk
+++ b/target/product/treble_common.mk
@@ -63,6 +63,11 @@
 PRODUCT_PACKAGES += \
     netutils-wrapper-1.0
 
+# Telephony:
+#   Provide a default APN configuration
+PRODUCT_COPY_FILES += \
+    device/generic/goldfish/data/etc/apns-conf.xml:system/etc/apns-conf.xml
+
 # Android Verified Boot (AVB):
 #   Builds a special vbmeta.img that disables AVB verification.
 #   Otherwise, AVB will prevent the device from booting the generic system.img.