Bluetooth: Re-organize logging Kconfig options

- got rid of "Others" menu
- JK I made a new one: "Common"
- moved all host-related opts to "Host" instead of "Others"
- moved all audio-related opts behind `if BT_AUDIO`
- moved only controller kconfig to controller/Kconfig.ll_sw_split
  - it had a dependency there already

Signed-off-by: Jonathan Rico <jonathan.rico@nordicsemi.no>