Add PermissionManager exposing SPLIT_PERMISSIONS

The Permission Controller app (a mainline module) needs to be able to
read the SPLIT_PERMISSIONS. Hence this array needs to be exposed at
least as system-api. We need to make sure that the PackageParser,
PackageManager and Permission Controller app agree on which permissions
are split, hence it is best to define them at a single location.

I think exposing the split permissions to developers is useless and
potentially confusing. The app should never request a permission that
was split. The app should just behave as if split permissions do not
exist. The Permission Controller / Package Manager deal with the
split permissions and add them when needed. Hence I don't think we
should expose this data to 3rd parties.

Bug: 110953302
Test: requested permissions
Change-Id: I6951c52979c89ee5c13a4a14da125e1a01f2e234