Allow IntentSender to use auto-opt-in

IntentSender methods pass in a special mode to flag the call a being
exempt from BAL hardening.
BackgroundActivityStartController funnels that flag to auto-opt in
logic, so the meaning is the same as opting in the call for another
reason, e.g. not being a PendingIntent, which means the logs won't see
this as an explicit opt-in.

Required refactorings:
New value in ActivityOptions, which means a switch from a boolean
tristate to an integer value.

Test: atest BackgroundActivityLaunchTest CtsAppTestCases:ActivityOptionsTest CtsAppTestCases:BroadcastOptionsTest
Bug: 339720406
Flag: EXEMPT bugfix
Change-Id: I507e9fed815884dae7c8a5a6b98a7deffc8e614a