[Companion] Show custom control names throughout the UI (& internal refactoring) (#4693)

* [Companion] Introduce new Boards class to further consolidate hardware metadata and remove some globals.

* [Companion] * RawSource::toString() and RawSwitch::toString() can now return custom hardware names (if given a GeneralSettings object) for the following types (respectively):
    SOURCE_TYPE_STICK, SOURCE_TYPE_SWITCH, SWITCH_TYPE_SWITCH, & SWITCH_TYPE_MULTIPOS_POT;
* RawSource::isPot() and isSlider() can now return their own index position in potConfig[]/sliderConfig[];
* Switch indicator strings can be localized if necessary.

* [Companion] Refactor model printers to use new RawSource/RawSwitch capabilities; Simplify model-to-printer mapping scheme in multimodelprinter; Use const ModelData pointer.

* [Companion] Refactor how RawSource and RawSwitch selection combo boxes are populated, using cache-able data models instead of direct manipulation; Refactor some other Helpers function into their own namespace.

* Cosmetics & forgotten qualifier.

companion/src/multimodelprinter.h

@@ -33,7 +33,8 @@ class MultiModelPrinter: public QObject
   public:
     MultiModelPrinter(Firmware * firmware);
     virtual ~MultiModelPrinter();
-    
+
+    void setModel(int idx, const ModelData & model, const GeneralSettings & generalSettings);
     void setModel(int idx, const ModelData & model);
     QString print(QTextDocument * document);
 
@@ -58,8 +59,7 @@ class MultiModelPrinter: public QObject
 
     Firmware * firmware;
     GeneralSettings defaultSettings;
-    QVector<ModelData *> models; // TODO const
-    QVector<ModelPrinter *> modelPrinters;
+    QMap<int, QPair<const ModelData *, ModelPrinter *> > modelPrinterMap;
 
     QString printTitle(const QString & label);
     QString printSetup();