broadcaster: Introduce intermediate states

This change introduces intermediate states which helps to manage
controller. There is need to do some controller actions with respect
to Audio Framework session callbacks e.g. remove BIG when session is
suspended before getting BIG create event.

Bug: 358587027
Bug: 360435489
Test: atest --host bluetooth_test_broadcaster_state_machine
Flag: TEST_ONLY
Change-Id: Id8b4fbc61061b8603aae6696b486faab8deefcd2