Add hot-gas reheat unitary system (Coil:Heating:Desuperheater)

[Ski90Moo]

Summary

• Adds "Unitary - Single Speed DX cooling - Elec heat - CAV - Desuperheater reheat" to the default HVAC library: the existing single-speed DX cooling coil paired with a new Coil:Heating:Desuperheater as the supplemental/reheat coil under CoolReheat dehumidification control, so reheat is partially sourced from the cooling coil's waste heat instead of just resistance heat.
• Fixes AirLoopHVACUnitarySystem/loop cloning (both "drag from library" and "Copy System"): ModelObject::clone() only remaps true parent-child relationships. Lateral (sibling-to-sibling) object-list references — like CoilHeatingDesuperheater::heatingSource(), or a SetpointManager:MixedAir's node fields — are left broken on the clone, sometimes stale, sometimes cleared outright. Added a generic post-clone reference fixup (buildCloneHandleMap + remapLateralReferences in HVACSystemsController.cpp, using IddObject::objectLists()/WorkspaceObject::getTarget()/setPointer()) rather than a Desuperheater-specific special case.
• The traversal walks children(), a loop's supplyComponents()/demandComponents(), and an outdoor air system's oaComponents()/reliefComponents() as independently size-matched groups, since branch equipment (units on a loop, or equipment like an evaporative cooler on an OA system's branches) isn't reachable via children() alone, and demand-side counts can legitimately differ between original and clone since connected thermal zones are never duplicated.

Context

Modeling dehumidification via hot-gas/desuperheater reheat is a recurring real-world need — see this UnmetHours thread, where CoilCoolingDXTwoStageWithHumidityControlMode proved awkward to control directly and commenters pointed toward Coil:Heating:Desuperheater as a workaround. Worth noting the thread's caveat: a desuperheater coil reclaims waste heat from the refrigerant's superheat and doesn't affect compressor performance, so it's a lower-fidelity approximation of "true" hot-gas reheat, not an exact substitute — but it's a standard, supported EnergyPlus object and a reasonable default-library addition for this use case.

Proof this was broken before this fix

You don't need the new desuperheater system to see the underlying bug — it reproduces with a completely stock model:

1. In the app, File > Examples > Example Model to generate a fresh example model.
2. Go to the HVAC Systems tab, select the one airloop, click "Copy System."
3. Select the copy and open its outdoor air system. It has an evaporative cooler with a SetpointManager:MixedAir attached — but on the copy, that setpoint manager's Reference Setpoint / Fan Inlet / Fan Outlet Node fields are all empty (shown as warning icons in the inspector), even though the original's are filled in correctly.
4. Run a simulation on the copy: EnergyPlus fails immediately with a fatal error (missing required properties on that object) before any calculation happens.

That's ModelObject::clone()'s lateral-reference bug on a totally unmodified example model — this PR's fixup resolves it for both this stock case and the new desuperheater system.

Test plan

• cmake --build . --target openstudio_lib --config Release succeeds
• Dragged the new system onto a zone in the app and ran the simulation successfully
• Used "Copy System" on that airloop, reassigned zones on the copy, and ran the simulation successfully
• Verified against the SDK directly (Ruby) for same-model/cross-model clone scenarios, and against OpenStudio::Model.exampleModel's stock outdoor-air-system evaporative cooler + SetpointManager:MixedAir
• Confirmed live in the rebuilt app that "Copy System" correctly re-wires node references on that stock example airloop too