arch: arm: BusFault, NMI, and HardFault in Secure state when in test

This commit enables the option to route the BusFault,
HardFault, and NMI exceptions in Secure state, when
building for Cortex-M CPUs with ARM_SECURE_FIRMWARE=y.
This allows the various test to utilize BusFault,
HardFault and NMI exceptions during testing.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>