feat: add HalDisplay and HalGPIO (#522)

## Summary

Extracted some changes from
https://github.com/crosspoint-reader/crosspoint-reader/pull/500 to make
reviewing easier

This PR adds HAL (Hardware Abstraction Layer) for display and GPIO
components, making it easier to write a stub or an emulated
implementation of the hardware.

SD card HAL will be added via another PR, because it's a bit more
tricky.

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? **NO**

src/MappedInputManager.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include <InputManager.h>
+#include <HalGPIO.h>
 
 class MappedInputManager {
  public:
@@ -13,7 +13,7 @@ class MappedInputManager {
     const char* btn4;
   };
 
-  explicit MappedInputManager(InputManager& inputManager) : inputManager(inputManager) {}
+  explicit MappedInputManager(HalGPIO& gpio) : gpio(gpio) {}
 
   bool wasPressed(Button button) const;
   bool wasReleased(Button button) const;
@@ -24,7 +24,7 @@ class MappedInputManager {
   Labels mapLabels(const char* back, const char* confirm, const char* previous, const char* next) const;
 
  private:
-  InputManager& inputManager;
+  HalGPIO& gpio;
 
-  bool mapButton(Button button, bool (InputManager::*fn)(uint8_t) const) const;
+  bool mapButton(Button button, bool (HalGPIO::*fn)(uint8_t) const) const;
 };