Test new READ/WRITE_EXTERNAL_STORAGE behavior.

In KLP, the platform now makes package-specific directories on
external storage available to apps without requiring they hold any
storage permissions.  This change uses three different packages to
verify behavior of apps with no permissions, with READ_EXTERNAL,
and with WRITE_EXTERNAL.  All three packages run a set of common
tests to verify that package-specific directories are always
writable.

Also verifies behavior of new APIs that provide access to secondary
external storage devices.  Specifically, apps only get write access
to their package-specific directories.  Apps holding WRITE_EXTERNAL
can only write outside their package-specific directories on primary
external storage.

Bug: 10577541
Change-Id: I467221c358fdc69f88d0df81d7ee50ad3c5ab5d5
10 files changed