Add support for replaceable models in Modelica templates

[AntoineGautier]

Currently ctrl-flow parser can only handle replaceable components inside Modelica templates.
This ticket is to add support for replaceable models.
Additional details are provided in the joint MBL issue lbl-srg/modelica-buildings#3507.

[AntoineGautier]

There is another issue that the branch issue3507_replaceableClass reveals.
In this branch, the component secRel of Buildings.Templates.AirHandlersFans.Components.OutdoorReliefReturnSection.MixedAirWithDamper is a simple replaceable component that should be visible in the configuration panel, but it isn't.
The corresponding option object in templates.json is:

    {
      "modelicaPath": "Buildings.Templates.AirHandlersFans.Components.OutdoorReliefReturnSection.MixedAirWithDamper.secRel",
      "type": "Buildings.Templates.AirHandlersFans.Components.ReliefReturnSection.ReturnFan",
      "value": "Buildings.Templates.AirHandlersFans.Components.ReliefReturnSection.ReturnFan",
      "name": "Relief/return air section",
      "group": "Configuration",
      "tab": "",
      "visible": true,
      "modifiers": {...},
      "enable": true,
      "choiceModifiers": {},
      "options": [
        "Buildings.Templates.AirHandlersFans.Components.ReliefReturnSection.ReturnFan",
        "Buildings.Templates.AirHandlersFans.Components.ReliefReturnSection.ReliefFan",
        "Buildings.Templates.AirHandlersFans.Components.ReliefReturnSection.ReliefDamper"
      ],
      "definition": false,
      "replaceable": true
    },

The following mods is not created by new ConfigContext:

    "secOutRel.secRel": {
      "value": "Buildings.Templates.AirHandlersFans.Components.ReliefReturnSection.ReliefDamper",
      "optionPath": "Buildings.Templates.AirHandlersFans.Components.OutdoorReliefReturnSection.MixedAirWithDamper.secRel"
    },

[EDIT] The component secRel isn't visible in the configuration form because its container component secOutRel isn't prefixed with replaceable in MBL commit a497569524. Adding the keyword replaceable, as in commit 6ca76bef6f, makes the component visible, as it should be.

However, this needs further investigation, considering the requirements from https://docs.google.com/document/d/1eFkCcZLmoi3Pkj9no54RaoPtwLqClGfx7cp7g8ORnZQ/edit?usp=sharing that specify that any instance of a model annotated with Dialog(...) with any dialog attribute except enable=false should be visible.