Remove PackageDataSnapshot and forAllPackageStates from API

It was decided to remove the snapshot from the API surface and
instead expose a wrapper which could be closed and better monitor
data flow.

This also does the real removal of forAllPackageStates which had
to be left in the API because of a build system prebuilt issue.

Bug: 244479008

Test: presubmit

Change-Id: I60c0c2f4e0d81e7b135404978988bf5e77a2b30b