Notify registrants when satellite modem enabled state changed

This change updates SatelliteController to notify registrants when
satellite enabled state has changed.

It also introduces unit test cases to cover the implementation.

Bug: 357638490
Test: atest FrameworksTelephonyTest
Flag: com.android.internal.telephony.flags.satellite_state_change_listener

Change-Id: I8d49a3a93f6d4b505bcc68fc63f426c7d4fd4bc1