Move 'privapp_whitelist_com.android.settings' to system_ext

As Settings is moved to system_ext, its permission files will follow the app location.

Test: m
Bug: 137908189
Change-Id: I58ae29a6454f91f222b15ccbd9d3e5b5d5889289
Merged-In: I58ae29a6454f91f222b15ccbd9d3e5b5d5889289