Adding an api which apps can query to check if the user has put them
into forced app standby.
An app may want to do this to manage expectations for any jobs or alarms
it schedules. It can also be used as an indication that the user noticed
unreasonable battery consumption attributed to the app.
Test: atest android.app.cts.ActivityManagerTest#testIsBackgroundRestricted
Bug: 73664209
Change-Id: I870f6c852c500769d3bf99d5a9ba3bf4eb1b65f5
4d64c093cd