soc: nordic: Add initial support for nRF9280 SiP

The nRF9280 is a SiP (System-in-Package) consisting of the nRF9230 SoC
and additional components such as PMIC and others. Additionally,
the nRF9230 contains several CPUs, similarly to the nRF54h20 SoC.

Update nrfx glue, and add necessary Kconfig and initialization code
to allow building for nRF9280 targets: CPU, Radio and PPR cores.

The nRF9280 is used for all user build targets and Kconfigs,
whereas the nRF9230 is used as the build target for the MDK.

Signed-off-by: Emanuele Di Santo <emdi@nordicsemi.no>
Co-authored-by: Andreas Moltumyr <andreas.moltumyr@nordicsemi.no>