Start bringing back legacy storage tests.

When APKs ask for the legacy storage world, we need the old tests to
verify they get the access they've been granted.  (For example, an
app only granted READ_EXTERNAL_STORAGE, etc.)

Bug: 130619210, 130566083
Test: atest android.appsecurity.cts.ExternalStorageHostTest
Change-Id: I943a7ea7ed6cb6728ec3bceb16edf1b2a7ad9b36