Return fatal error in ApplicationInit()

[MonicaisHer]

https://github.com/canonical/matter-mqtt-bridge/blob/555e1d3590d0b5b39fa479c18b052797eee42fce/app/bridge-app/linux/main.cpp#L823-L871 This should be a fatal error.

Originally posted by @farshidtz in https://github.com/canonical/matter-mqtt-bridge/pull/1#discussion_r1305550340

In order to return a fatal error, we might consider modifying the return value of ApplicationInit(). Another option could be to throw an exception or return the fatal error via an out parameter and handle it accordingly.