Plumb through volume UUID when building paths.

Since app data paths can live on expanded storage devices, accept the
target volume UUID when building paths.  The null UUID indicates the
default internal storage.

To improve readability, start using std::string in several places,
which throws when allocations fail.  For now, perform last-second
sanity checks on incoming path arguments, but we'll eventually want
to check arguments as they come through installd.cpp, instead of
crashing the entire daemon.

Also remove "lib" symlink code from install() and make_user_data(),
since we're no longer supporting /data/app-lib.  The framework
already uses linklib() to create the right symlink for the selected
ISA-specific library dir.

Bug: 19993667
Change-Id: Ib9343575ffb62bf3981e19375de8f3822fc31e28