Move isArchived into the PackageItemInfo class.

I'm making this change to enable us to load the archived icon instead of
the standard icon when loadIcon is called on the ApplicationInfo of an
archived app.

Icon related logic is in the PackageItemInfo class and we might want
to set isArchived for the archived activities we construct in
LauncherApps later on as well. So this class seems like the best fit.

Test: PackageInstallerArchiveTest.java
Bug: 298375566

Change-Id: I0a130d5ff862af733b4f3dbe3a515b94d82ec7ce