Bluetooth: Audio: Media - refactor include discovery start
Bluetooth: Audio: Media - refactor include discovery start

Move the start of discovery of included services to a separate
function, in preparation for rewriting discovery.

Signed-off-by: Asbjørn Sæbø <79238bdce2d54e50328756ad5a8d04b51bb621fe@nordicsemi.no>

zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr