APIs to suspend packages with SUSPEND_APPS permission

Changed the existing hidden api setPackagesSuspendedAsUser to a system
api setPackagesSuspended that can be called by apps with either
MANAGE_USERS or SUSPEND_APPS permission. Additionally, the suspending
app can now specify optional extra information meant to be used by the
suspended apps and the launcher to deal with this state.

The following other APIs are added:
 - isPackageSuspended(): Apps can query whether they are in a suspended
 state
 - @SystemApi getPackageSuspendedAppExtras(String): Apps with permission
 SUSPEND_APPS can get the appExtras passed to PM when suspending the
 app.
 - @SystemApi setPackageSuspendedAppExtras(String, PersistableBundle):
 Apps with permission SUSPEND_APPS can update app extras for a
 suspended package.
 - getPackageSuspendedAppExtras(): Apps can call to get the appExtras
 passed in to PM when they were suspended.

Test: Can be run via:
atest com.android.server.pm.PackageManagerSettingsTests
atest com.android.server.pm.PackageUserStateTest
atest com.android.server.pm.SuspendPackagesTest

Bug: 74336673
Change-Id: I3b9ed2c8478b34ee2e8986f5f5fddb2839d102e3