[client/idd] input: synchronize keyboard LEDs

Report guest HID keyboard LED state from LGInput to LGIdd and
publish it with the LGMP input endpoint status.

Forward SPICE modifier updates through the same provider state so evdev
can synchronize physical keyboard LEDs across transport changes and
reconnects.

Bump the versioned pipe and KVMFR input status contracts for the new
feedback state.

Accept earlier LGMP input status versions without LED feedback so the
client retains input while the guest driver is being upgraded.

idd/LGIdd/transport/CInputHub.cpp

@@ -551,6 +551,8 @@ InputTargetState CInputHub::GetState(const SourceKey& source)
     return result;
   if (!BindingValid(source))
     return result;
+  result.keyboardLEDsValid = m_sink->GetKeyboardLEDs(
+    result.keyboardLEDs);
   if (!m_owner.backend)
     result.available = true;
   else if (source.client && source.generation && m_owner == source)