[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/simulation/simulatorinterface.h

@@ -41,7 +41,7 @@ struct TxInputs
     int  switches[CPN_MAX_SWITCHES];
     bool keys[CPN_MAX_KEYS];
     bool rotenc;
-    bool trims[(CPN_MAX_STICKS + CPN_MAX_AUX_TRIMS) * 2];
+    bool trims[CPN_MAX_TRIM_SW];
 };
 
 class TxOutputs
@@ -57,7 +57,7 @@ class TxOutputs
 
 struct Trims
 {
-  int values[CPN_MAX_STICKS + CPN_MAX_AUX_TRIMS]; /* lh lv rv rh t5 t6 */
+  int values[CPN_MAX_TRIMS]; /* lh lv rv rh t5 t6 */
   bool extended;
 };