Watch face selection at build time

Watch faces can now be selected at buid time. It's implemented in a similar way than the selection of user apps, using a list of watch face description that is generated at build time (consteval, constexpr)

src/displayapp/screens/WatchFaceAnalog.h

@@ -88,5 +88,23 @@ namespace Pinetime {
         lv_task_t* taskRefresh;
       };
     }
+
+    template <>
+    struct WatchFaceTraits<WatchFace::Analog> {
+      static constexpr WatchFace watchFace = WatchFace::Analog;
+      static constexpr const char* name = "Analog face";
+
+      static Screens::Screen* Create(AppControllers& controllers) {
+        return new Screens::WatchFaceAnalog(controllers.dateTimeController,
+                                            controllers.batteryController,
+                                            controllers.bleController,
+                                            controllers.notificationManager,
+                                            controllers.settingsController);
+      };
+
+      static bool IsAvailable(Pinetime::Controllers::FS& /*filesystem*/) {
+        return true;
+      }
+    };
   }
 }