fix a lot of low level cppcheck warnings (#9623)

* simplify the observer pattern, since all the called functions are const getters.
* use arduino macro over std: for numerical values and refactor local variables in drawScrollbar()
* oh, so Cppcheck actually complained about const pointers not being const.
* slowly getting out of ifdef hell
* fix inkHUD warnings as well
* last 2 check warnings
* git checks should fail on low defects from now on

src/graphics/niche/InkHUD/MessageStore.h

@@ -31,7 +31,7 @@ class MessageStore
     };
 
     MessageStore() = delete;
-    explicit MessageStore(std::string label); // Label determines filename in flash
+    explicit MessageStore(const std::string &label); // Label determines filename in flash
 
     void saveToFlash();
     void loadFromFlash();