This moves fstrim, obb and appfuse commands over to the new Binder
interface. This change also separates creating/destroying and
mounting/unmounting of OBB volumes, which means they finally flow
nicely into the modern VolumeInfo/VolumeBase design.
We now generate unique identifiers for all OBB volumes, instead of
using a shady MD5 hash.
Change all "loop" and "dm" devices to tag the kernel resources with
a vold-specific prefix so that we can clean them up if vold crashes;
there are new destroyAll() methods that handle this cleanup.
Move appfuse mounting/unmounting into VolumeManager so it can be
shared. Move various model objects into a separate directory to
tidy things up.
Test: cts-tradefed run commandAndExit cts-dev -m CtsOsTestCases -t android.os.storage.cts.StorageManagerTest
Bug: 13758960
Change-Id: I7294e32b3fb6efe07cb3b77bd20166e70b66958f
