Add fake 31.0 prebuilt

This commit adds fake 31.0 prebuilt. The prebuilt is based on AOSP
policy, but slightly modified so the set of types and attributes is a
subset of real 31.0 prebuilt (sc-dev policy).

Steps taken to make the fake prebuilt:

1) build plat_sepolicy.cil both on AOSP and sc-dev, with lunch target
aosp_arm64-eng.
2) diff both outputs to find out which types and attributes don't exist.
3) remove all relevant files and statements.

As a result, the following types are removed.

artd
artd_exec
artd_service
power_stats_service
transformer_service
virtualizationservice
virtualizationservice_data_file
virtualizationservice_exec

Bug: 189161483
Test: N/A, will do after adding 31.0 mapping files.
Change-Id: Ia957fc32b1838dae730d9dd7bd917d684d4a24cf
Merged-In: Ia4ea2999f4bc8ae80f13e51d99fba3e98e293447
436 files changed