samples: bluetooth: iso_receive: Convert to new k_work API
samples: bluetooth: iso_receive: Convert to new k_work API

Converts the sample to the new k_work API, and introduces a blink
boolean to catch cancel failures.

Signed-off-by: Trond Einar Snekvik <cbf21a7cf058d7ce8e74b0726695057d761f6ae9@nordicsemi.no>

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