Support composite bindings with record instances

[AntoineGautier]

Testing the app with MBL HP plant template shows that toggling the following parameter does not change the set of exposed parameters in the section "Plant controller" of the configuration panel. All parameters related to the CHW circuit should be disabled if have_chiWat=false, as with Modelica tools.

  parameter Boolean have_chiWat=true
    "Set to true if the plant provides CHW"

A probable cause is the following composite parameter binding cfg=cfg that is used to propagate all configuration parameters from the template to its controller.

  replaceable Buildings.Templates.Plants.HeatPumps.Components.Interfaces.PartialController ctl
    constrainedby 
    Buildings.Templates.Plants.HeatPumps.Components.Interfaces.PartialController(
      final cfg=cfg,
      final dat=dat.ctl)
    "Plant controller"