Add a module for accessing guest memory.
This module will replace all the slices that are used to access it
currently as those slices aren't valid because the memory is volatile
and a volatile slice doesn't exist in rust.
Modify the existing users so they no longer depend on the deprecated slice
access.
Change-Id: Ic0e86dacf66f68bd88ed9cc197cb14e45ada891d
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/509919