sepolicy: Add entry for wifi apex mainline module

Bug: 144722612
Test: Device boots up & connects to wifi networks
Change-Id: If9207075b87dc938926c1fc1432d3b8fe481bc02
diff --git a/apex/com.android.wifi-file_contexts b/apex/com.android.wifi-file_contexts
new file mode 100644
index 0000000..f3a65d4
--- /dev/null
+++ b/apex/com.android.wifi-file_contexts
@@ -0,0 +1 @@
+(/.*)?                u:object_r:system_file:s0