sys: interrupts: add shared interrupts support

[d4ilyrun]

Shared interrupts

Some devices may need to share a single interrupt line. This is the case for legacy PCI devices that
share the same interrupt line, originating from the PCI root complex.

Implementation idea

Use a list of interrupt handlers structures instead of a single interrupt handler. The default_interrupt_handler()
function should walk along this list, and each handler should first check whether the interrupts they are meant
to handle have been raised (using the device's registers).