floss: Refactor btstack initialization order (3/4 BluetoothMedia)

This patch does:
- Reverse the dependency - Now BluetoothMedia depends on Bluetooth and
  media is optional in Bluetooth. This makes more sense in the context
  of Bluetooth because it inits earlier than media.
- Since the dependency is reversed we can now init BluetoothMedia later,
  and save many redundant `Option` in BluetoothMedia.

Some backgrounds:
  We want to get rid of the redundant `Option` of the topshim objects
  that is causing many verbosities and confusing snippets (We all know
  we can't do anything without the objects... Then why is it optional?).
  The overall direction is to remove all Bluetooth's dependencies on
  initialization, because the Bluetooth topshim object needs to be
  initialized first before all other topshim objects can be obtained.

Bug: 254870880
Tag: #floss
Test: mmm packages/modules/Bluetooth
Test: bluetooth_AdapterQuickHealth.AVL.all_floss
Test: manual Allegro HFP and A2DP
Flag: EXEMPT, Floss-only changes
Change-Id: If1b81374363755d1a826d8b60c32d41453f5b4a2