Add apex_available to resolver

Apex module "com.android.wifi" only exists in internal master.
If we use dnsresolver_aidl_interface-unstable-java, it would cause
build error.

Bug: 149733540
Test: m -j
Merged-In: I38d922e07b32d415755c66ddeb97c44aa816e0c2
Change-Id: I7b0d0c825560bc494ff7be1f03b12996ef1eb31c