The HIDController class is removed and instead adding SerialIOController
class. The HIDController class was a mistake - there's no such thing in
real hardware as host controller only for human interface devices
(VirtIO PCI input controller being the exception here, but it could be
technically treated as serial IO controller too).
Instead, we simply add a new abstraction layer - the SerialIO "bus",
which will hold all the code that is related to serial communications
with other devices. A PS2 controller is simply a serial IO controller,
and the Intel 8042 Controller is simply a specific implementation of a
PS2 controller.
Use the new class in HID code, because all other HID device controllers
will be using this class as their parent class.
Hence, we no longer keep a reference to any PS/2 device in HIDManagement
and rely on HIDController derived classes to do this for us.
It also means that we removed another instance of a LockRefPtr, which
is designated to be removed and is replaced by the better pattern of
SpinlockProtected<RefPtr<>> instead.
