Create app-metadata directory

App metadata bundles, also known as Android Safety Labels (ASL),
contains information about the app's privacy and security practices.
This information is used to help users make more informed choices when,
for example, granting access to permissions.

ASL can currently only be preloaded on the system image or distributed
by the installer and written to a file in the app's codePath. To support
embedded ASL in APK we need to extract ASLs from APKs to a writeable
location. For non-preloaded apps we can write to the app's codePath like
the installer provided ASLs, however, we need to create a new writable
directory for preloaded apps located on read only partitions.

Bug: 336618214
Test: manual
Change-Id: I651b2dab45c3132d8467c507dc4ee304001f73f5