Add permission check to UsageStatsManager#isAppInactive

UsageStatsManager#isAppInactive provides usage information that is
usually gated by the PACKAGE_USAGE_STATS permission in similar API.
This updates isAppInactive to also check for the PACKAGE_USAGE_STATS
permission.

Test: atest android.app.usage.cts android.app.usage.cts.UsageStatsTest#testIsAppInactive
Fixes: 148991455

Change-Id: I8ff8eb5d2e887bc164095f38d374e3992808fe79