add @TestApi hasForegroundServiceDelegation in TelecomManager

This CL adds a new test api that is useful for checking the foreground
service state of a particular app

Flag: com.android.server.telecom.flags.voip_call_monitor_refactor
Bug: 381129034
Test: cts + unit tests + manual
Change-Id: I30caf014ea06f3e6122234ecfd5368571e8ee3b9