Ignore APEX packages in UPS (i.e. in V+).

APEX packages aren't supposed to be able to declare permissions, and
they shouldn't have permission states either since they don't even have
app IDs (their PackageState.appId is -1). So within UPS we should just
ignore APEX packages.

Since we don't want to make a copy of the packageStates from
PackageManagerLocal, we can only manually skip the APEX packages during
iterations for now.

Bug: 301320911
Test: presubmit
Test: dumpsys permissionmgr
Change-Id: I10f89ddd386bb6a4d2ae62b8193014ad7679189a