Connect and bond with a passkey

This commit adds the following:
    Passkey pairing - passkey is displayed on watch
    Swipe down to clear passkey screen
    Connection encryption
    Connection bonding
    Automatic reconnects to a bonded peripheral
    Trusted device on Android

Note that persisting the bond between reboots is NOT included in
this commit. Therefore, rebooting the watch will cause reconnect failures.
You must delete the bond from the phone to reconnect/pair.

src/displayapp/Apps.h

@@ -25,6 +25,7 @@ namespace Pinetime {
       Metronome,
       Motion,
       Steps,
+      PassKey,
       QuickSettings,
       Settings,
       SettingWatchFace,

src/displayapp/DisplayApp.cpp

@@ -29,6 +29,7 @@
 #include "displayapp/screens/FlashLight.h"
 #include "displayapp/screens/BatteryInfo.h"
 #include "displayapp/screens/Steps.h"
+#include "displayapp/screens/PassKey.h"
 #include "displayapp/screens/Error.h"
 
 #include "drivers/Cst816s.h"
@@ -288,6 +289,9 @@ void DisplayApp::Refresh() {
         // Added to remove warning
         // What should happen here?
         break;
+      case Messages::ShowPairingKey:
+        LoadApp(Apps::PassKey, DisplayApp::FullRefreshDirections::Up);
+        break;
     }
   }
 
@@ -351,6 +355,11 @@ void DisplayApp::LoadApp(Apps app, DisplayApp::FullRefreshDirections direction)
       ReturnApp(Apps::Clock, FullRefreshDirections::Down, TouchEvents::None);
       break;
 
+    case Apps::PassKey:
+      currentScreen = std::make_unique<Screens::PassKey>(this, bleController.GetPairingKey());
+      ReturnApp(Apps::Clock, FullRefreshDirections::Down, TouchEvents::SwipeDown);
+      break;
+
     case Apps::Notifications:
       currentScreen = std::make_unique<Screens::Notifications>(
         this, notificationManager, systemTask->nimble().alertService(), motorController, Screens::Notifications::Modes::Normal);

src/displayapp/Messages.h

@@ -19,6 +19,7 @@ namespace Pinetime {
         UpdateTimeOut,
         DimScreen,
         RestoreBrightness,
+        ShowPairingKey,
         AlarmTriggered
       };
     }

src/displayapp/screens/PassKey.cpp

@@ -0,0 +1,17 @@
+#include "PassKey.h"
+#include "displayapp/DisplayApp.h"
+
+using namespace Pinetime::Applications::Screens;
+
+PassKey::PassKey(Pinetime::Applications::DisplayApp* app, uint32_t key) : Screen(app) {
+  lpasskey = lv_label_create(lv_scr_act(), nullptr);
+  lv_obj_set_style_local_text_color(lpasskey, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, lv_color_hex(0xFFFF00));
+  lv_obj_set_style_local_text_font(lpasskey, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, &jetbrains_mono_42);
+  lv_label_set_text_fmt(lpasskey, "%06u", key);
+  lv_obj_align(lpasskey, nullptr, LV_ALIGN_CENTER, 0, -20);
+}
+
+PassKey::~PassKey() {
+  lv_obj_clean(lv_scr_act());
+}
+

src/displayapp/screens/PassKey.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include "Screen.h"
+#include <lvgl/lvgl.h>
+
+namespace Pinetime {
+  namespace Applications {
+    namespace Screens {
+
+      class PassKey : public Screen {
+      public:
+        PassKey(DisplayApp* app, uint32_t key);
+        ~PassKey() override;
+
+      private:
+        lv_obj_t* lpasskey;
+      };
+    }
+  }
+}