hw: remove deprecated param check in Signal_root

ref #1123
hw: unravel classes in signal_session_component.h

ref #1123
hw: non-pragmatic dimensioning of signal slabs

ref #1123
hw: use constexpr in signal_session_component.h

ref #1123
hw: fix redundancy in signal_session_component.h

ref #1123
hw: raise max amount of signal contexts

This is needed at least for the resource-request test since all available
interrupts are provided through a signal context.

fix #1123